9 CSS Tab Switch Animations — gần như chỉ CSS

<main class="stage">
  <div class="us is-demo">
    <input type="radio" name="us-tab" id="us-1" class="us__radio" checked>
    <input type="radio" name="us-tab" id="us-2" class="us__radio">
    <input type="radio" name="us-tab" id="us-3" class="us__radio">
    <div class="us__nav">
      <label class="us__tab" for="us-1">Tổng quan</label>
      <label class="us__tab" for="us-2">Phân tích</label>
      <label class="us__tab" for="us-3">Cài đặt</label>
      <span class="us__indicator" aria-hidden="true"></span>
    </div>
    <div class="us__panels">
      <p class="us__panel us__panel--1">Xem lượt truy cập hôm nay và các chỉ số chính trong một cái nhìn.</p>
      <p class="us__panel us__panel--2">So sánh xu hướng theo thời gian bằng bảng và biểu đồ.</p>
      <p class="us__panel us__panel--3">Quản lý thông báo và quyền của nhóm trong tab này.</p>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;                            // 인디케이터가 미끄러지는 시간
$easing: $ease-spring;                            // 인디케이터 전환 이징 (실제 클릭)
$color: $subject-blue;                            // 인디케이터 색

@include stage($stage-ink);

.us { width: min(320px, 88vw); }
.us__radio { position: absolute; opacity: 0; pointer-events: none; }

.us__nav {
  position: relative;
  isolation: isolate;             // ::after 트레일(z -1)이 인디케이터 뒤에만 그려지게 (2026-09-15 한 겹)
  display: grid;
  grid-template-columns: repeat(3, 1fr);
}
.us__tab {
  padding: $sp-3 $sp-2;
  text-align: center;
  font-weight: 600;
  font-size: clamp(13px, 3.6vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: rgba(255, 247, 230, .6);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.us__indicator {
  position: absolute; left: 0; bottom: 0;
  width: calc(100% / 3); height: 3px;
  background: $color;
  border-radius: $r-pill;
  transform: translateX(0);
  transition: transform $duration $easing;
}
// 한 겹(관성 오버슛 + 트레일): ::after 만 추가 — index.html·레이아웃 불변.
// 트레일은 인디케이터 자신이 아니라 .us__nav(고정 컨테이너)의 ::after 로 둔다 — 만약 인디케이터
// 자신의 ::after 로 두면 부모의 진행 중인 transform 위에 트레일 자신의 transform 이 겹쳐 더해져
// (중첩 transform 합성) 이동거리가 배로 튄다. nav 는 움직이지 않으므로 트레일만의 절대 좌표
// keyframes 가 그대로 유효하다. 정적(:checked) 전환에서는 .is-demo 스코프 밖이라 animation 이
// 전혀 안 걸려 opacity 0 그대로 안 보인다. 트레일 색은 $color 파생 rgba 만 쓴다.
.us__nav::after {
  content: "";
  position: absolute; left: 0; bottom: 0;
  z-index: -1;
  width: calc(100% / 3); height: 3px;
  border-radius: $r-pill;
  background: rgba($color, .35);
  filter: blur(2px);
  opacity: 0;
}

// ── 실제 동작: :checked 만으로 인디케이터가 옮겨간다 ──────────────
#us-1:checked ~ .us__nav .us__indicator { transform: translateX(0%); }
#us-2:checked ~ .us__nav .us__indicator { transform: translateX(100%); }
#us-3:checked ~ .us__nav .us__indicator { transform: translateX(200%); }
#us-1:checked ~ .us__nav label[for="us-1"],
#us-2:checked ~ .us__nav label[for="us-2"],
#us-3:checked ~ .us__nav label[for="us-3"] { color: $subject-cream; }

// 패널 세 개를 같은 grid 칸에 포개 두면 인디케이터와 함께 바뀌어도 자리가 안 흔들린다
.us__panels { position: relative; display: grid; margin-top: $sp-4; min-height: 40px; }
.us__panel {
  grid-area: 1 / 1;
  margin: 0;
  color: rgba(255, 247, 230, .82);
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
  opacity: 0;
  transition: opacity $duration $easing;
}
#us-1:checked ~ .us__panels .us__panel--1,
#us-2:checked ~ .us__panels .us__panel--2,
#us-3:checked ~ .us__panels .us__panel--3 { opacity: 1; }

// ── 데모 루프: 클릭 전까지 세 탭을 스스로 오간다 (인디케이터·패널이 같은 박자) ──────────────
// us-loop → us-loop-inertia: 33%/66% 도착 전에 살짝 지나쳤다가(108%/216%) 관성처럼 되돌아와 정착한다.
.us.is-demo .us__indicator { animation: us-loop-inertia $dur-loop $easing infinite; }
// 트레일은 인디케이터와 같은 이동을 120ms 늦게 따라오다 도착 뒤 옅어지며 사라진다.
.us.is-demo .us__nav::after { animation: us-trail-loop $dur-loop $easing infinite; animation-delay: 120ms; }
.us.is-demo .us__panel--1 { animation: us-panel-1 $dur-loop $easing infinite; }
.us.is-demo .us__panel--2 { animation: us-panel-2 $dur-loop $easing infinite; }
.us.is-demo .us__panel--3 { animation: us-panel-3 $dur-loop $easing infinite; }
@keyframes us-loop-inertia {
  0%, 15%  { transform: translateX(0%); }
  30%      { transform: translateX(108%); }
  33%, 48% { transform: translateX(100%); }
  63%      { transform: translateX(216%); }
  66%, 81% { transform: translateX(200%); }
  100%     { transform: translateX(0%); }
}
// 트레일 전용: 같은 이동 경로 + opacity 를 얹어 "따라오다 옅어지는" 잔상으로 읽히게 한다.
@keyframes us-trail-loop {
  0%, 15%  { transform: translateX(0%);   opacity: 0; }
  24%      { opacity: .35; }
  30%      { transform: translateX(108%); opacity: .35; }
  33%, 40% { transform: translateX(100%); opacity: .35; }
  48%      { transform: translateX(100%); opacity: 0; }
  63%      { transform: translateX(216%); opacity: .35; }
  66%, 73% { transform: translateX(200%); opacity: .35; }
  81%      { transform: translateX(200%); opacity: 0; }
  100%     { transform: translateX(0%);   opacity: 0; }
}
@keyframes us-panel-1 { 0%, 15% { opacity: 1; } 30%, 100% { opacity: 0; } }
@keyframes us-panel-2 { 0%, 30% { opacity: 0; } 45%, 63% { opacity: 1; } 78%, 100% { opacity: 0; } }
@keyframes us-panel-3 { 0%, 63% { opacity: 0; } 78%, 96% { opacity: 1; } 100% { opacity: 0; } }

// ── 접근성 ──────────────────────────────────────────
@media (prefers-reduced-motion: reduce) {
  .us__indicator, .us__panel { transition: none; }
  .us.is-demo .us__indicator,
  .us.is-demo .us__nav::after,
  .us.is-demo .us__panel--1,
  .us.is-demo .us__panel--2,
  .us.is-demo .us__panel--3 { animation: none !important; }
  .us__nav::after { opacity: 0; } // 관성·트레일 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.us {
  width: min(320px, 88vw);
}

.us__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.us__nav {
  position: relative;
  isolation: isolate;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
}

.us__tab {
  padding: 12px 8px;
  text-align: center;
  font-weight: 600;
  font-size: clamp(13px, 3.6vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: rgba(255, 247, 230, 0.6);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.us__indicator {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 33.3333333333%;
  height: 3px;
  background: #2f6df6;
  border-radius: 999px;
  transform: translateX(0);
  transition: transform 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.us__nav::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  z-index: -1;
  width: 33.3333333333%;
  height: 3px;
  border-radius: 999px;
  background: rgba(47, 109, 246, 0.35);
  filter: blur(2px);
  opacity: 0;
}

#us-1:checked ~ .us__nav .us__indicator {
  transform: translateX(0%);
}

#us-2:checked ~ .us__nav .us__indicator {
  transform: translateX(100%);
}

#us-3:checked ~ .us__nav .us__indicator {
  transform: translateX(200%);
}

#us-1:checked ~ .us__nav label[for=us-1],
#us-2:checked ~ .us__nav label[for=us-2],
#us-3:checked ~ .us__nav label[for=us-3] {
  color: #fff7e6;
}

.us__panels {
  position: relative;
  display: grid;
  margin-top: 16px;
  min-height: 40px;
}

.us__panel {
  grid-area: 1/1;
  margin: 0;
  color: rgba(255, 247, 230, 0.82);
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
  opacity: 0;
  transition: opacity 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

#us-1:checked ~ .us__panels .us__panel--1,
#us-2:checked ~ .us__panels .us__panel--2,
#us-3:checked ~ .us__panels .us__panel--3 {
  opacity: 1;
}

.us.is-demo .us__indicator {
  animation: us-loop-inertia 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.us.is-demo .us__nav::after {
  animation: us-trail-loop 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
  animation-delay: 120ms;
}

.us.is-demo .us__panel--1 {
  animation: us-panel-1 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.us.is-demo .us__panel--2 {
  animation: us-panel-2 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.us.is-demo .us__panel--3 {
  animation: us-panel-3 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes us-loop-inertia {
  0%, 15% {
    transform: translateX(0%);
  }
  30% {
    transform: translateX(108%);
  }
  33%, 48% {
    transform: translateX(100%);
  }
  63% {
    transform: translateX(216%);
  }
  66%, 81% {
    transform: translateX(200%);
  }
  100% {
    transform: translateX(0%);
  }
}
@keyframes us-trail-loop {
  0%, 15% {
    transform: translateX(0%);
    opacity: 0;
  }
  24% {
    opacity: 0.35;
  }
  30% {
    transform: translateX(108%);
    opacity: 0.35;
  }
  33%, 40% {
    transform: translateX(100%);
    opacity: 0.35;
  }
  48% {
    transform: translateX(100%);
    opacity: 0;
  }
  63% {
    transform: translateX(216%);
    opacity: 0.35;
  }
  66%, 73% {
    transform: translateX(200%);
    opacity: 0.35;
  }
  81% {
    transform: translateX(200%);
    opacity: 0;
  }
  100% {
    transform: translateX(0%);
    opacity: 0;
  }
}
@keyframes us-panel-1 {
  0%, 15% {
    opacity: 1;
  }
  30%, 100% {
    opacity: 0;
  }
}
@keyframes us-panel-2 {
  0%, 30% {
    opacity: 0;
  }
  45%, 63% {
    opacity: 1;
  }
  78%, 100% {
    opacity: 0;
  }
}
@keyframes us-panel-3 {
  0%, 63% {
    opacity: 0;
  }
  78%, 96% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .us__indicator, .us__panel {
    transition: none;
  }
  .us.is-demo .us__indicator,
  .us.is-demo .us__nav::after,
  .us.is-demo .us__panel--1,
  .us.is-demo .us__panel--2,
  .us.is-demo .us__panel--3 {
    animation: none !important;
  }
  .us__nav::after {
    opacity: 0;
  }
}

// 이동은 :checked 만으로 이미 동작한다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.us__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.us').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./UnderlineSlide.module.scss";

const TABS = [
  { label: "개요", panel: "오늘 방문자와 핵심 지표를 한눈에 봅니다." },
  { label: "분석", panel: "기간별 추이를 표와 그래프로 비교합니다." },
  { label: "설정", panel: "알림과 팀 권한을 이 탭에서 관리합니다." },
];

export type UnderlineSlideProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--i"?: number };

export default function UnderlineSlide({ duration = 300, easing = "cubic-bezier(.2,.8,.2,1)", color = "#2f6df6" }: UnderlineSlideProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--i": active };

  return (
    <div className={styles.us} style={vars}>
      <div className={styles.nav} role="tablist">
        {TABS.map((t, i) => (
          <button key={t.label} type="button" role="tab" aria-selected={i === active}
                  className={styles.tab} onClick={() => setActive(i)}>
            {t.label}
          </button>
        ))}
        <span className={styles.indicator} aria-hidden="true" />
      </div>
      <p className={styles.panel}>{TABS[active].panel}</p>
    </div>
  );
}

<main class="stage">
  <div class="pi is-demo">
    <input type="radio" name="pi-tab" id="pi-1" class="pi__radio" checked>
    <input type="radio" name="pi-tab" id="pi-2" class="pi__radio">
    <input type="radio" name="pi-tab" id="pi-3" class="pi__radio">
    <div class="pi__nav">
      <span class="pi__pill" aria-hidden="true"></span>
      <label class="pi__tab" for="pi-1">Tất cả</label>
      <label class="pi__tab" for="pi-2">Tháng này</label>
      <label class="pi__tab" for="pi-3">Năm nay</label>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-quick;                            // 필이 옮겨가는 시간
$easing: $ease-pop;                               // 필 전환 이징 (실제 클릭)
$color: $subject-blue-deep;                       // 필 배경 색 — 잉크 글자가 4.03 으로 미달이라 짙은 파랑으로 (크림 글자 5.98:1)

@include stage($stage-yellow);

// 라벨 글자 수가 다르므로 폭·이동 거리를 항목마다 고정값으로 둔다
// (함정: 라벨을 바꾸면 이 값도 같이 바꿔야 한다 — 자동으로 안 맞다)
// 값은 짐작이 아니라 실측이다 (Playwright getBoundingClientRect, 480×300) — 짐작값(56/76/56)은
// .pi__tab 이 flex:1 1 0(균등분배)일 때만 우연히 비슷했고, flex:0 0 auto(내용 폭)로 고치니 실제 폭은
// 37/52/37 이었다 (사용자 2026-09-10 스크린샷 "필이 딴 데 걸림" 지적, BD19)
$w1: 37px; $w2: 52px; $w3: 37px;

.pi { width: min(280px, 84vw); }
.pi__radio { position: absolute; opacity: 0; pointer-events: none; }

.pi__nav {
  position: relative;
  isolation: isolate;             // ::after 트레일(z -1)이 필 뒤에만 그려지게 (2026-09-15 한 겹)
  display: flex;
  gap: $sp-2;
  padding: $sp-1;
  background: rgba(23, 20, 26, .08);
  border-radius: $r-pill;
}
// 글자색의 기본은 잉크다 — 무대(노랑) 위에서 10.8:1. 필 위에 온(:checked) 글자만 크림(5.98:1)으로 바뀐다.
// 데모 루프에서는 아래 pi-ink-* 키프레임이 필과 같은 박자로 글자색을 옮긴다 — 필이 떠난 자리의 크림 글자가 노란 무대 위에서 사라지는 일이 없다
.pi__tab {
  position: relative; z-index: 1;
  flex: 0 0 auto;                                   // 내용 폭 — 균등분배(1 1 0)면 아래 필 지오메트리 상수와 어긋난다 (BD19)
  text-align: center;
  padding: $sp-2 $sp-1;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: $subject-ink;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.pi__pill {
  position: absolute; top: $sp-1; left: $sp-1; bottom: $sp-1;
  width: $w1;
  border-radius: $r-pill;
  background: $color;
  transform: translateX(0) scaleX(1);
  transform-origin: left center; // 규칙8: 좌변 기준 좌표·배율 계산
  transition: transform $duration $easing;
}
// 한 겹(관성+트레일)은 ::after 만 추가 — index.html·레이아웃 불변. 트레일은 필 자신이 아니라
// .pi__nav(고정 컨테이너)의 ::after 로 둔다 — 필 자신의 ::after 로 두면 부모의 진행 중인
// transform 위에 트레일 자신의 transform 이 겹쳐 더해져(중첩 transform 합성) 이동거리·스케일이
// 배로 튄다. nav 는 움직이지 않으므로 트레일만의 절대 좌표 keyframes 가 그대로 유효하다.
// 정적(:checked) 전환에선 .is-demo 스코프 밖이라 animation 이 안 걸려 opacity 0 그대로 안 보인다.
.pi__nav::after {
  content: "";
  position: absolute; top: $sp-1; left: $sp-1; bottom: $sp-1;
  z-index: -1;
  width: $w1;
  border-radius: $r-pill;
  background: rgba($color, .3);
  filter: blur(2px);
  transform: translateX(0) scaleX(1);
  transform-origin: left center;
  opacity: 0;
}

// scaleX 비율은 컴파일 시점 상수로 미리 계산한다 (calc() 안에서 길이÷길이는 CSS 스펙상 무효라 런타임 계산 불가)
$scale2: 1.405; // #{$w2} / #{$w1}
$scale3: 1;      // #{$w3} / #{$w1}

// ── 실제 동작: :checked 만으로 필이 이동·변형된다 ──────────────
#pi-1:checked ~ .pi__nav .pi__pill { transform: translateX(0) scaleX(1); }
#pi-2:checked ~ .pi__nav .pi__pill { transform: translateX(calc(#{$w1} + #{$sp-2})) scaleX(#{$scale2}); }
#pi-3:checked ~ .pi__nav .pi__pill { transform: translateX(calc(#{$w1} + #{$w2} + #{$sp-2} * 2)) scaleX(#{$scale3}); }
// 필 위에 온 글자만 크림 — 잉크를 그대로 두면 짙은 파랑 위 2.87:1 이다
#pi-1:checked ~ .pi__nav label[for="pi-1"],
#pi-2:checked ~ .pi__nav label[for="pi-2"],
#pi-3:checked ~ .pi__nav label[for="pi-3"] { color: $subject-cream; }

// ── 데모 루프: 클릭 전까지 세 필터를 스스로 오간다 ──────────────
.pi.is-demo .pi__pill { animation: pi-loop $dur-loop $easing infinite; }
.pi.is-demo .pi__nav::after { animation: pi-trail-loop $dur-loop $easing infinite; animation-delay: 120ms; }
// 글자색도 필과 같은 박자(0·15/33·48/66·81/100%)로 — 크림 글자가 필 없는 자리에 남지 않게
.pi.is-demo .pi__nav label[for="pi-1"] { animation: pi-ink-1 $dur-loop linear infinite; }
.pi.is-demo .pi__nav label[for="pi-2"] { animation: pi-ink-2 $dur-loop linear infinite; }
.pi.is-demo .pi__nav label[for="pi-3"] { animation: pi-ink-3 $dur-loop linear infinite; }
@keyframes pi-ink-1 { 0%, 15% { color: $subject-cream; } 23%, 87% { color: $subject-ink; } 95%, 100% { color: $subject-cream; } }
@keyframes pi-ink-2 { 0%, 25% { color: $subject-ink; } 33%, 48% { color: $subject-cream; } 56%, 100% { color: $subject-ink; } }
@keyframes pi-ink-3 { 0%, 58% { color: $subject-ink; } 66%, 81% { color: $subject-cream; } 89%, 100% { color: $subject-ink; } }
// pi-loop 오버슛 보강 — 각 도착 전 지점에서 scaleX 는 목표값을 미리 유지한 채 translateX 만
// 5px 살짝 지나쳤다가(관성) 정착한다.
@keyframes pi-loop {
  0%, 15%  { transform: translateX(0) scaleX(1); }
  30%      { transform: translateX(calc(#{$w1} + #{$sp-2} + 5px)) scaleX(#{$scale2}); }
  33%, 48% { transform: translateX(calc(#{$w1} + #{$sp-2})) scaleX(#{$scale2}); }
  63%      { transform: translateX(calc(#{$w1} + #{$w2} + #{$sp-2} * 2 + 5px)) scaleX(#{$scale3}); }
  66%, 81% { transform: translateX(calc(#{$w1} + #{$w2} + #{$sp-2} * 2)) scaleX(#{$scale3}); }
  96%      { transform: translateX(-5px) scaleX(1); }
  100%     { transform: translateX(0) scaleX(1); }
}
// 트레일 전용 — 같은 모양(같은 scaleX)을 120ms 늦게 쫓아가며 옅어진다
@keyframes pi-trail-loop {
  0%, 15%  { transform: translateX(0) scaleX(1); opacity: 0; }
  24%      { opacity: .3; }
  30%      { transform: translateX(calc(#{$w1} + #{$sp-2} + 5px)) scaleX(#{$scale2}); opacity: .3; }
  33%, 40% { transform: translateX(calc(#{$w1} + #{$sp-2})) scaleX(#{$scale2}); opacity: .3; }
  48%      { transform: translateX(calc(#{$w1} + #{$sp-2})) scaleX(#{$scale2}); opacity: 0; }
  63%      { transform: translateX(calc(#{$w1} + #{$w2} + #{$sp-2} * 2 + 5px)) scaleX(#{$scale3}); opacity: .3; }
  66%, 73% { transform: translateX(calc(#{$w1} + #{$w2} + #{$sp-2} * 2)) scaleX(#{$scale3}); opacity: .3; }
  81%      { transform: translateX(calc(#{$w1} + #{$w2} + #{$sp-2} * 2)) scaleX(#{$scale3}); opacity: 0; }
  100%     { transform: translateX(0) scaleX(1); opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .pi__pill { transition: none; }
  .pi.is-demo .pi__pill,
  .pi.is-demo .pi__nav::after { animation: none !important; }
  .pi.is-demo .pi__nav label { animation: none !important; } // 색 애니메이션도 끈다 — 글자색은 :checked(크림)·기본(잉크) 로만
  .pi__nav::after { opacity: 0; } // 관성·트레일 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.pi {
  width: min(280px, 84vw);
}

.pi__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.pi__nav {
  position: relative;
  isolation: isolate;
  display: flex;
  gap: 8px;
  padding: 4px;
  background: rgba(23, 20, 26, 0.08);
  border-radius: 999px;
}

.pi__tab {
  position: relative;
  z-index: 1;
  flex: 0 0 auto;
  text-align: center;
  padding: 8px 4px;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.pi__pill {
  position: absolute;
  top: 4px;
  left: 4px;
  bottom: 4px;
  width: 37px;
  border-radius: 999px;
  background: #0a4fe8;
  transform: translateX(0) scaleX(1);
  transform-origin: left center;
  transition: transform 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}

.pi__nav::after {
  content: "";
  position: absolute;
  top: 4px;
  left: 4px;
  bottom: 4px;
  z-index: -1;
  width: 37px;
  border-radius: 999px;
  background: rgba(10, 79, 232, 0.3);
  filter: blur(2px);
  transform: translateX(0) scaleX(1);
  transform-origin: left center;
  opacity: 0;
}

#pi-1:checked ~ .pi__nav .pi__pill {
  transform: translateX(0) scaleX(1);
}

#pi-2:checked ~ .pi__nav .pi__pill {
  transform: translateX(calc(37px + 8px)) scaleX(1.405);
}

#pi-3:checked ~ .pi__nav .pi__pill {
  transform: translateX(calc(37px + 52px + 8px * 2)) scaleX(1);
}

#pi-1:checked ~ .pi__nav label[for=pi-1],
#pi-2:checked ~ .pi__nav label[for=pi-2],
#pi-3:checked ~ .pi__nav label[for=pi-3] {
  color: #fff7e6;
}

.pi.is-demo .pi__pill {
  animation: pi-loop 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

.pi.is-demo .pi__nav::after {
  animation: pi-trail-loop 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
  animation-delay: 120ms;
}

.pi.is-demo .pi__nav label[for=pi-1] {
  animation: pi-ink-1 2s linear infinite;
}

.pi.is-demo .pi__nav label[for=pi-2] {
  animation: pi-ink-2 2s linear infinite;
}

.pi.is-demo .pi__nav label[for=pi-3] {
  animation: pi-ink-3 2s linear infinite;
}

@keyframes pi-ink-1 {
  0%, 15% {
    color: #fff7e6;
  }
  23%, 87% {
    color: #17141a;
  }
  95%, 100% {
    color: #fff7e6;
  }
}
@keyframes pi-ink-2 {
  0%, 25% {
    color: #17141a;
  }
  33%, 48% {
    color: #fff7e6;
  }
  56%, 100% {
    color: #17141a;
  }
}
@keyframes pi-ink-3 {
  0%, 58% {
    color: #17141a;
  }
  66%, 81% {
    color: #fff7e6;
  }
  89%, 100% {
    color: #17141a;
  }
}
@keyframes pi-loop {
  0%, 15% {
    transform: translateX(0) scaleX(1);
  }
  30% {
    transform: translateX(calc(37px + 8px + 5px)) scaleX(1.405);
  }
  33%, 48% {
    transform: translateX(calc(37px + 8px)) scaleX(1.405);
  }
  63% {
    transform: translateX(calc(37px + 52px + 8px * 2 + 5px)) scaleX(1);
  }
  66%, 81% {
    transform: translateX(calc(37px + 52px + 8px * 2)) scaleX(1);
  }
  96% {
    transform: translateX(-5px) scaleX(1);
  }
  100% {
    transform: translateX(0) scaleX(1);
  }
}
@keyframes pi-trail-loop {
  0%, 15% {
    transform: translateX(0) scaleX(1);
    opacity: 0;
  }
  24% {
    opacity: 0.3;
  }
  30% {
    transform: translateX(calc(37px + 8px + 5px)) scaleX(1.405);
    opacity: 0.3;
  }
  33%, 40% {
    transform: translateX(calc(37px + 8px)) scaleX(1.405);
    opacity: 0.3;
  }
  48% {
    transform: translateX(calc(37px + 8px)) scaleX(1.405);
    opacity: 0;
  }
  63% {
    transform: translateX(calc(37px + 52px + 8px * 2 + 5px)) scaleX(1);
    opacity: 0.3;
  }
  66%, 73% {
    transform: translateX(calc(37px + 52px + 8px * 2)) scaleX(1);
    opacity: 0.3;
  }
  81% {
    transform: translateX(calc(37px + 52px + 8px * 2)) scaleX(1);
    opacity: 0;
  }
  100% {
    transform: translateX(0) scaleX(1);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .pi__pill {
    transition: none;
  }
  .pi.is-demo .pi__pill,
  .pi.is-demo .pi__nav::after {
    animation: none !important;
  }
  .pi.is-demo .pi__nav label {
    animation: none !important;
  }
  .pi__nav::after {
    opacity: 0;
  }
}

// 필 배경은 :checked 만으로 옮겨간다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.pi__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.pi').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./PillIndicator.module.scss";

const TABS = ["전체", "이번달", "올해"];
const WIDTHS = [56, 76, 56];      // 라벨 글자 수가 다르므로 폭을 고정값으로 둔다 (함정: 라벨을 바꾸면 값도 같이 바꿔야 한다)
const GAP = 8;

export type PillIndicatorProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--x"?: string; "--scale"?: number };

export default function PillIndicator({ duration = 220, easing = "cubic-bezier(.2,1.4,.4,1)", color = "#0a4fe8" }: PillIndicatorProps) {
  const [active, setActive] = useState(0);
  const x = WIDTHS.slice(0, active).reduce((a, w) => a + w + GAP, 0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--x": `${x}px`, "--scale": WIDTHS[active] / WIDTHS[0] };

  return (
    <div className={styles.pi} style={vars}>
      <div className={styles.nav} role="tablist">
        <span className={styles.pill} aria-hidden="true" />
        {TABS.map((t, i) => (
          <button key={t} type="button" role="tab" aria-selected={i === active}
                  className={styles.tab} onClick={() => setActive(i)}>
            {t}
          </button>
        ))}
      </div>
    </div>
  );
}

<main class="stage">
  <div class="fp is-demo">
    <input type="radio" name="fp-tab" id="fp-1" class="fp__radio" checked>
    <input type="radio" name="fp-tab" id="fp-2" class="fp__radio">
    <input type="radio" name="fp-tab" id="fp-3" class="fp__radio">
    <div class="fp__nav">
      <label class="fp__tab" for="fp-1">Giới thiệu</label>
      <label class="fp__tab" for="fp-2">Đánh giá</label>
      <label class="fp__tab" for="fp-3">Hỏi đáp</label>
    </div>
    <div class="fp__panels">
      <p class="fp__panel fp__panel--1">Tổng hợp chất liệu, kích cỡ và cách giặt.</p>
      <p class="fp__panel fp__panel--2">Tổng hợp 342 đánh giá và nhận xét gần đây.</p>
      <p class="fp__panel fp__panel--3">Yêu cầu đổi trả hoặc hoàn tiền ngay tại đây.</p>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-quick;                            // 패널이 겹쳐 페이드되는 시간
$easing: $ease-out;                               // 패널 페이드 이징 (실제 클릭)
$color: $subject-ink;                             // 활성 탭 글자색 (주황 면 위 5.50:1 — 크림은 3.11 로 미달)

@include stage($stage-orange);

.fp { width: min(300px, 86vw); }
.fp__radio { position: absolute; opacity: 0; pointer-events: none; }

.fp__nav {
  position: relative;
  display: flex;
  gap: $sp-4;
  border-bottom: 1px solid rgba(255, 247, 230, .25);
  padding-bottom: $sp-2;
}
.fp__tab {
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: rgba($subject-ink, .85);                 // 비활성 탭 — 주황 면 위 4.62:1 (.72 는 3.76 으로 미달)
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
#fp-1:checked ~ .fp__nav label[for="fp-1"],
#fp-2:checked ~ .fp__nav label[for="fp-2"],
#fp-3:checked ~ .fp__nav label[for="fp-3"] { color: $color; }

// 세 패널을 같은 grid 칸에 포개 두면 자리가 안 흔들린다
.fp__panels { position: relative; display: grid; margin-top: $sp-4; min-height: 40px; }
.fp__panel {
  grid-area: 1 / 1;
  margin: 0;
  color: $subject-ink;                            // 패널 본문 — 5.50:1
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
  opacity: 0;
  pointer-events: none;
  transition: opacity $duration $easing;
}
#fp-1:checked ~ .fp__panels .fp__panel--1,
#fp-2:checked ~ .fp__panels .fp__panel--2,
#fp-3:checked ~ .fp__panels .fp__panel--3 { opacity: 1; pointer-events: auto; }

// ── 데모 루프: 클릭 전까지 세 패널을 스스로 오간다 ──────────────
// 한 겹(관성) — 밑줄이 없는 이 항목은 패널 전환에 관성을 얹는다: 등장 패널은 8px 아래에서
// 올라와 -2px 살짝 지나쳤다가(오버슛) 0 에 정착, 사라지는 패널은 반대로 2px 위로 흐르며 fade.
// 정적(:checked) 전환 경로는 opacity 만인 원본 그대로 — 관성은 -inertia 루프 키프레임 안에서만.
.fp.is-demo .fp__panel--1 { animation: fp-loop-1-inertia $dur-loop $easing infinite; }
.fp.is-demo .fp__panel--2 { animation: fp-loop-2-inertia $dur-loop $easing infinite; }
.fp.is-demo .fp__panel--3 { animation: fp-loop-3-inertia $dur-loop $easing infinite; }
@keyframes fp-loop-1-inertia {
  0%, 15%  { opacity: 1; transform: translateY(0); }
  22%      { transform: translateY(-1px); }
  30%, 100% { opacity: 0; transform: translateY(-2px); }
}
@keyframes fp-loop-2-inertia {
  0%, 30%   { opacity: 0; transform: translateY(8px); }
  42%       { transform: translateY(-2px); }
  45%, 63%  { opacity: 1; transform: translateY(0); }
  70%       { transform: translateY(-1px); }
  78%, 100% { opacity: 0; transform: translateY(-2px); }
}
@keyframes fp-loop-3-inertia {
  0%, 63%   { opacity: 0; transform: translateY(8px); }
  75%       { transform: translateY(-2px); }
  78%, 96%  { opacity: 1; transform: translateY(0); }
  98%       { transform: translateY(-1px); }
  100%      { opacity: 0; transform: translateY(-2px); }
}

@media (prefers-reduced-motion: reduce) {
  .fp__panel { transition: none; }
  .fp.is-demo .fp__panel--1,
  .fp.is-demo .fp__panel--2,
  .fp.is-demo .fp__panel--3 { animation: none !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.fp {
  width: min(300px, 86vw);
}

.fp__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.fp__nav {
  position: relative;
  display: flex;
  gap: 16px;
  border-bottom: 1px solid rgba(255, 247, 230, 0.25);
  padding-bottom: 8px;
}

.fp__tab {
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: rgba(23, 20, 26, 0.85);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

#fp-1:checked ~ .fp__nav label[for=fp-1],
#fp-2:checked ~ .fp__nav label[for=fp-2],
#fp-3:checked ~ .fp__nav label[for=fp-3] {
  color: #17141a;
}

.fp__panels {
  position: relative;
  display: grid;
  margin-top: 16px;
  min-height: 40px;
}

.fp__panel {
  grid-area: 1/1;
  margin: 0;
  color: #17141a;
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
  opacity: 0;
  pointer-events: none;
  transition: opacity 220ms ease-out;
}

#fp-1:checked ~ .fp__panels .fp__panel--1,
#fp-2:checked ~ .fp__panels .fp__panel--2,
#fp-3:checked ~ .fp__panels .fp__panel--3 {
  opacity: 1;
  pointer-events: auto;
}

.fp.is-demo .fp__panel--1 {
  animation: fp-loop-1-inertia 2s ease-out infinite;
}

.fp.is-demo .fp__panel--2 {
  animation: fp-loop-2-inertia 2s ease-out infinite;
}

.fp.is-demo .fp__panel--3 {
  animation: fp-loop-3-inertia 2s ease-out infinite;
}

@keyframes fp-loop-1-inertia {
  0%, 15% {
    opacity: 1;
    transform: translateY(0);
  }
  22% {
    transform: translateY(-1px);
  }
  30%, 100% {
    opacity: 0;
    transform: translateY(-2px);
  }
}
@keyframes fp-loop-2-inertia {
  0%, 30% {
    opacity: 0;
    transform: translateY(8px);
  }
  42% {
    transform: translateY(-2px);
  }
  45%, 63% {
    opacity: 1;
    transform: translateY(0);
  }
  70% {
    transform: translateY(-1px);
  }
  78%, 100% {
    opacity: 0;
    transform: translateY(-2px);
  }
}
@keyframes fp-loop-3-inertia {
  0%, 63% {
    opacity: 0;
    transform: translateY(8px);
  }
  75% {
    transform: translateY(-2px);
  }
  78%, 96% {
    opacity: 1;
    transform: translateY(0);
  }
  98% {
    transform: translateY(-1px);
  }
  100% {
    opacity: 0;
    transform: translateY(-2px);
  }
}
@media (prefers-reduced-motion: reduce) {
  .fp__panel {
    transition: none;
  }
  .fp.is-demo .fp__panel--1,
  .fp.is-demo .fp__panel--2,
  .fp.is-demo .fp__panel--3 {
    animation: none !important;
  }
}

// 페이드는 :checked 만으로 이미 동작한다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.fp__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.fp').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./FadePanel.module.scss";

const TABS = [
  { label: "소개", panel: "소재·사이즈·세탁법을 정리했습니다." },
  { label: "리뷰", panel: "별점과 최근 구매평 342건을 모았습니다." },
  { label: "문의", panel: "교환·환불은 여기서 바로 신청하세요." },
];

export type FadePanelProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function FadePanel({ duration = 220, easing = "ease-out", color = "#17141a" }: FadePanelProps) { // 주황 무대 위 활성 탭 글자 — 크림은 3.11 로 미달
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.fp} style={vars}>
      <div className={styles.nav} role="tablist">
        {TABS.map((t, i) => (
          <button key={t.label} type="button" role="tab" aria-selected={i === active}
                  className={styles.tab} onClick={() => setActive(i)}>
            {t.label}
          </button>
        ))}
      </div>
      <div className={styles.panels}>
        {TABS.map((t, i) => (
          <p key={t.label} className={styles.panel} style={{ opacity: i === active ? 1 : 0 }} aria-hidden={i !== active}>
            {t.panel}
          </p>
        ))}
      </div>
    </div>
  );
}

<main class="stage">
  <div class="sp is-demo">
    <input type="radio" name="sp-tab" id="sp-1" class="sp__radio" checked>
    <input type="radio" name="sp-tab" id="sp-2" class="sp__radio">
    <input type="radio" name="sp-tab" id="sp-3" class="sp__radio">
    <div class="sp__nav">
      <label class="sp__tab" for="sp-1">Bước 1</label>
      <label class="sp__tab" for="sp-2">Bước 2</label>
      <label class="sp__tab" for="sp-3">Bước 3</label>
      <span class="sp__indicator" aria-hidden="true"></span>
    </div>
    <div class="sp__viewport">
      <div class="sp__track">
        <p class="sp__panel">Nhập địa chỉ giao hàng.</p>
        <p class="sp__panel">Chọn phương thức thanh toán.</p>
        <p class="sp__panel">Xác nhận đơn hàng và hoàn tất.</p>
      </div>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;                             // 패널 트랙이 밀리는 시간
$easing: $ease-out;                               // 트랙·밑줄 공용 이징 (트랙은 이 한 겹에서 건드리지 않는다)
$color: $subject-blue;                            // 활성 탭 밑줄 색

@include stage($stage-paper);

.sp { width: min(300px, 86vw); }
.sp__radio { position: absolute; opacity: 0; pointer-events: none; }

.sp__nav {
  position: relative;
  isolation: isolate;             // ::after 트레일(z -1)이 인디케이터 뒤에만 그려지게 (2026-09-15 한 겹)
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin-bottom: $sp-3;
  border-bottom: 1px solid rgba(23, 20, 26, .12);
}
.sp__tab {
  padding-bottom: $sp-2;
  text-align: center;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: $subject-ink;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
// 탭 셋 아래 밑줄 하나가 옮겨간다 — 트랙과 같은 :checked·같은 박자라 어긋나지 않는다
.sp__indicator {
  position: absolute; left: 0; bottom: -1px;
  width: calc(100% / 3); height: 2px;
  background: $color;
  transform: translateX(0%);
  transition: transform $duration $easing;
}
// 한 겹(관성+트레일)은 인디케이터(밑줄)에만 — ::after 만 추가, index.html·트랙 불변.
// 트레일은 인디케이터 자신이 아니라 .sp__nav(고정 컨테이너)의 ::after 로 둔다 — 인디케이터 자신의
// ::after 로 두면 부모의 진행 중인 transform 위에 트레일 자신의 transform 이 겹쳐 더해져(중첩
// transform 합성) 이동거리가 배로 튄다. nav 는 움직이지 않으므로 트레일만의 절대 좌표 keyframes
// 가 그대로 유효하다. 정적(:checked) 전환에서는 .is-demo 스코프 밖이라 animation 이 안 걸려
// opacity 0 그대로다.
.sp__nav::after {
  content: "";
  position: absolute; left: 0; bottom: -1px;
  z-index: -1;
  width: calc(100% / 3); height: 2px;
  background: rgba($color, .35);
  filter: blur(2px);
  opacity: 0;
}
#sp-1:checked ~ .sp__nav .sp__indicator { transform: translateX(0%); }
#sp-2:checked ~ .sp__nav .sp__indicator { transform: translateX(100%); }
#sp-3:checked ~ .sp__nav .sp__indicator { transform: translateX(200%); }

// 패널 세 장을 나란히 두고 트랙 전체를 옮긴다 — width 가 아니라 transform 만 쓴다
.sp__viewport { overflow: hidden; }
.sp__track {
  display: flex;
  width: 300%;
  transform: translateX(0%);
  transition: transform $duration $easing;
}
.sp__panel {
  flex: 0 0 calc(100% / 3);
  margin: 0;
  box-sizing: border-box;
  padding-right: $sp-4;
  color: rgba(23, 20, 26, .8);
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
}

// ── 실제 동작: :checked 만으로 트랙이 밀려난다 ──────────────
#sp-1:checked ~ .sp__viewport .sp__track { transform: translateX(0%); }
#sp-2:checked ~ .sp__viewport .sp__track { transform: translateX(-33.333%); }
#sp-3:checked ~ .sp__viewport .sp__track { transform: translateX(-66.667%); }

// ── 데모 루프: 클릭 전까지 세 단계를 스스로 오간다 (밑줄·트랙이 같은 박자) ──────────────
// 트랙(.sp__track)은 건드리지 않는다 — 콘텐츠 이동에 오버슛을 주면 어색하다. sp-loop 원본 그대로.
.sp.is-demo .sp__track { animation: sp-loop $dur-loop $easing infinite; }
// 밑줄(인디케이터)만 오버슛 보강 — sp-indicator-loop 안에 30%/63% 지나침 스텝을 추가(이름은 유지)
.sp.is-demo .sp__indicator { animation: sp-indicator-loop $dur-loop $easing infinite; }
.sp.is-demo .sp__nav::after { animation: sp-trail-loop $dur-loop $easing infinite; animation-delay: 120ms; }
@keyframes sp-loop {
  0%, 15%  { transform: translateX(0%); }
  33%, 48% { transform: translateX(-33.333%); }
  66%, 81% { transform: translateX(-66.667%); }
  100%     { transform: translateX(0%); }
}
@keyframes sp-indicator-loop {
  0%, 15%  { transform: translateX(0%); }
  30%      { transform: translateX(108%); }
  33%, 48% { transform: translateX(100%); }
  63%      { transform: translateX(216%); }
  66%, 81% { transform: translateX(200%); }
  100%     { transform: translateX(0%); }
}
// 트레일 전용 — 같은 경로를 120ms 늦게 쫓아가며 옅어진다 (1번과 동일 패턴)
@keyframes sp-trail-loop {
  0%, 15%  { transform: translateX(0%);   opacity: 0; }
  24%      { opacity: .35; }
  30%      { transform: translateX(108%); opacity: .35; }
  33%, 40% { transform: translateX(100%); opacity: .35; }
  48%      { transform: translateX(100%); opacity: 0; }
  63%      { transform: translateX(216%); opacity: .35; }
  66%, 73% { transform: translateX(200%); opacity: .35; }
  81%      { transform: translateX(200%); opacity: 0; }
  100%     { transform: translateX(0%);   opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .sp__track, .sp__indicator { transition: none; }
  .sp.is-demo .sp__track,
  .sp.is-demo .sp__indicator,
  .sp.is-demo .sp__nav::after { animation: none !important; }
  .sp__nav::after { opacity: 0; } // 관성·트레일 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.sp {
  width: min(300px, 86vw);
}

.sp__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.sp__nav {
  position: relative;
  isolation: isolate;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin-bottom: 12px;
  border-bottom: 1px solid rgba(23, 20, 26, 0.12);
}

.sp__tab {
  padding-bottom: 8px;
  text-align: center;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.sp__indicator {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 33.3333333333%;
  height: 2px;
  background: #2f6df6;
  transform: translateX(0%);
  transition: transform 300ms ease-out;
}

.sp__nav::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  z-index: -1;
  width: 33.3333333333%;
  height: 2px;
  background: rgba(47, 109, 246, 0.35);
  filter: blur(2px);
  opacity: 0;
}

#sp-1:checked ~ .sp__nav .sp__indicator {
  transform: translateX(0%);
}

#sp-2:checked ~ .sp__nav .sp__indicator {
  transform: translateX(100%);
}

#sp-3:checked ~ .sp__nav .sp__indicator {
  transform: translateX(200%);
}

.sp__viewport {
  overflow: hidden;
}

.sp__track {
  display: flex;
  width: 300%;
  transform: translateX(0%);
  transition: transform 300ms ease-out;
}

.sp__panel {
  flex: 0 0 33.3333333333%;
  margin: 0;
  box-sizing: border-box;
  padding-right: 16px;
  color: rgba(23, 20, 26, 0.8);
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
}

#sp-1:checked ~ .sp__viewport .sp__track {
  transform: translateX(0%);
}

#sp-2:checked ~ .sp__viewport .sp__track {
  transform: translateX(-33.333%);
}

#sp-3:checked ~ .sp__viewport .sp__track {
  transform: translateX(-66.667%);
}

.sp.is-demo .sp__track {
  animation: sp-loop 2s ease-out infinite;
}

.sp.is-demo .sp__indicator {
  animation: sp-indicator-loop 2s ease-out infinite;
}

.sp.is-demo .sp__nav::after {
  animation: sp-trail-loop 2s ease-out infinite;
  animation-delay: 120ms;
}

@keyframes sp-loop {
  0%, 15% {
    transform: translateX(0%);
  }
  33%, 48% {
    transform: translateX(-33.333%);
  }
  66%, 81% {
    transform: translateX(-66.667%);
  }
  100% {
    transform: translateX(0%);
  }
}
@keyframes sp-indicator-loop {
  0%, 15% {
    transform: translateX(0%);
  }
  30% {
    transform: translateX(108%);
  }
  33%, 48% {
    transform: translateX(100%);
  }
  63% {
    transform: translateX(216%);
  }
  66%, 81% {
    transform: translateX(200%);
  }
  100% {
    transform: translateX(0%);
  }
}
@keyframes sp-trail-loop {
  0%, 15% {
    transform: translateX(0%);
    opacity: 0;
  }
  24% {
    opacity: 0.35;
  }
  30% {
    transform: translateX(108%);
    opacity: 0.35;
  }
  33%, 40% {
    transform: translateX(100%);
    opacity: 0.35;
  }
  48% {
    transform: translateX(100%);
    opacity: 0;
  }
  63% {
    transform: translateX(216%);
    opacity: 0.35;
  }
  66%, 73% {
    transform: translateX(200%);
    opacity: 0.35;
  }
  81% {
    transform: translateX(200%);
    opacity: 0;
  }
  100% {
    transform: translateX(0%);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .sp__track, .sp__indicator {
    transition: none;
  }
  .sp.is-demo .sp__track,
  .sp.is-demo .sp__indicator,
  .sp.is-demo .sp__nav::after {
    animation: none !important;
  }
  .sp__nav::after {
    opacity: 0;
  }
}

// 이동은 :checked 만으로 이미 동작한다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.sp__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.sp').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./SlidePanel.module.scss";

const TABS = [
  { label: "1단계", panel: "배송지를 입력합니다." },
  { label: "2단계", panel: "결제 수단을 고릅니다." },
  { label: "3단계", panel: "주문을 확인하고 완료합니다." },
];

export type SlidePanelProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--i"?: number };

export default function SlidePanel({ duration = 300, easing = "ease-out", color = "#2f6df6" }: SlidePanelProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--i": active };

  return (
    <div className={styles.sp} style={vars}>
      <div className={styles.nav} role="tablist">
        {TABS.map((t, i) => (
          <button key={t.label} type="button" role="tab" aria-selected={i === active}
                  className={styles.tab} onClick={() => setActive(i)}>
            {t.label}
          </button>
        ))}
      </div>
      <div className={styles.viewport}>
        <div className={styles.track}>
          {TABS.map((t) => <p key={t.label} className={styles.panel}>{t.panel}</p>)}
        </div>
      </div>
    </div>
  );
}

<main class="stage">
  <div class="it is-demo" role="tablist" aria-label="Điều hướng phía dưới">
    <button class="it__tab" type="button" role="tab" aria-selected="true" tabindex="0">
      <svg class="it__icon" viewBox="0 0 24 24" width="22" height="22" aria-hidden="true"><path d="M4 11 12 4l8 7v8a1 1 0 0 1-1 1h-4v-6H9v6H5a1 1 0 0 1-1-1z" fill="currentColor"/></svg>
      <span class="it__label">Trang chủ</span>
    </button>
    <button class="it__tab" type="button" role="tab" aria-selected="false" tabindex="-1">
      <svg class="it__icon" viewBox="0 0 24 24" width="22" height="22" aria-hidden="true"><circle cx="10" cy="10" r="6" fill="none" stroke="currentColor" stroke-width="2"/><line x1="15" y1="15" x2="20" y2="20" stroke="currentColor" stroke-width="2" stroke-linecap="round"/></svg>
      <span class="it__label">Tìm kiếm</span>
    </button>
    <button class="it__tab" type="button" role="tab" aria-selected="false" tabindex="-1">
      <svg class="it__icon" viewBox="0 0 24 24" width="22" height="22" aria-hidden="true"><circle cx="12" cy="8" r="4" fill="currentColor"/><path d="M4 21c0-4.4 3.6-7 8-7s8 2.6 8 7" fill="currentColor"/></svg>
      <span class="it__label">Cá nhân</span>
    </button>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-quick;                            // 아이콘이 커지는 시간
$easing: $ease-pop;                               // 아이콘 바운스 이징
$color: $subject-cream;                           // 활성 아이콘·라벨 색

@include stage($stage-ink);

.it {
  display: flex;
  gap: $sp-6;
  padding: $sp-3 $sp-6;
  border-radius: $r-card;
  background: rgba(255, 255, 255, .06);
}
.it__tab {
  position: relative;                             // 트레일 고리(::before) 의 좌표 기준 (2026-09-15 형태 2차)
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-1;
  border: 0;
  background: none;
  padding: $sp-1;
  color: rgba($subject-cream, .75);               // 카드 면 위 8.85:1 (.5 였고 라벨 opacity .7 과 곱해 3.06 으로 미달였다)
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.it__icon { position: relative; z-index: 1; transform: scale(1); transition: transform $duration $easing; color: inherit; } // z-index 1 — 잔상 고리(::before)를 아이콘 뒤로 깐다
.it__label { font-weight: 600; font-size: clamp(10px, 2.8vw, 11px); line-height: 1; font-family: inherit; opacity: 1; transition: opacity $duration $easing; } // 부모 색 알파(.75)가 이미 흐림을 담당 — opacity 를 곱하면 다시 미달로 떨어진다

.it__tab[aria-selected="true"] { color: $color; }
.it__tab[aria-selected="true"] .it__icon { transform: scale(1.18); }
.it__tab[aria-selected="true"] .it__label { opacity: 1; }

// 한 겹(잔상 트레일) — 아이콘 바운스에 원형 흐림 잔상을 얹는다. .it__icon 은 <svg> 인데
// SVG 요소에는 ::before/::after 가 박스를 만들지 않으므로(브라우저 공통 — SVG 는 가상요소
// 콘텐츠 삽입을 지원하지 않는다) 탭 버튼 위에 ::before 로 두고 아이콘 중심에 맞춘다.
// ::before 는 콘텐츠보다 먼저 칠해져 아이콘 뒤에 깔린다(z-index 낮음 등가). 아이콘 22px +
// inset -4px 등가 = 30px 원. 정적(aria-selected) 상태엔 opacity 0 — .is-demo 에서만 움직인다.
.it__tab::before {
  content: "";
  position: absolute;
  top: calc(#{$sp-1} + 11px);                     // 아이콘 세로 중심 — 패딩 4px + 22px 아이콘의 절반
  left: 50%;
  width: 30px; height: 30px;
  margin: -15px 0 0 -15px;                        // 중심 정렬 — transform 은 키프레임 scale 전용
  border-radius: 50%;
  background: rgba($color, .2);
  filter: blur(2px);
  opacity: 0;
  pointer-events: none;
}

// ── 데모 루프: 클릭 전까지 세 아이콘을 순서대로 튕긴다 ──────────────
.it.is-demo .it__tab:nth-child(1) .it__icon { animation: it-bump $dur-loop $easing infinite; }
.it.is-demo .it__tab:nth-child(2) .it__icon { animation: it-bump $dur-loop $easing infinite; animation-delay: calc($dur-loop / 3 * -2); }
.it.is-demo .it__tab:nth-child(3) .it__icon { animation: it-bump $dur-loop $easing infinite; animation-delay: calc($dur-loop / 3 * -1); }
@keyframes it-bump {
  0%, 8%, 100% { transform: scale(1); }
  4%           { transform: scale(1.18); }
}
// 잔상 고리도 it-bump 와 같은 nth-child 위상 — 각 탭이 튕기는 순간에 scale 오버슛 후 fade
.it.is-demo .it__tab:nth-child(1)::before { animation: it-trail-loop $dur-loop ease-out infinite; }
.it.is-demo .it__tab:nth-child(2)::before { animation: it-trail-loop $dur-loop ease-out infinite; animation-delay: calc($dur-loop / 3 * -2); }
.it.is-demo .it__tab:nth-child(3)::before { animation: it-trail-loop $dur-loop ease-out infinite; animation-delay: calc($dur-loop / 3 * -1); }
@keyframes it-trail-loop {
  0%       { transform: scale(.6);  opacity: 0; }
  2%       { transform: scale(1.1); opacity: .2; }  // 아이콘이 튀는 순간 살짝 지나쳤다가
  6%       { transform: scale(1.25); opacity: .16; }
  12%, 100% { transform: scale(1.6); opacity: 0; }  // 펴지며 잔상처럼 사라진다
}

@media (prefers-reduced-motion: reduce) {
  .it__icon, .it__label { transition: none; }
  .it.is-demo .it__tab .it__icon,
  .it.is-demo .it__tab::before { animation: none !important; }
  .it__tab::before { opacity: 0; } // 잔상 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.it {
  display: flex;
  gap: 24px;
  padding: 12px 24px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.06);
}

.it__tab {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  border: 0;
  background: none;
  padding: 4px;
  color: rgba(255, 247, 230, 0.75);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.it__icon {
  position: relative;
  z-index: 1;
  transform: scale(1);
  transition: transform 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
  color: inherit;
}

.it__label {
  font-weight: 600;
  font-size: clamp(10px, 2.8vw, 11px);
  line-height: 1;
  font-family: inherit;
  opacity: 1;
  transition: opacity 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}

.it__tab[aria-selected=true] {
  color: #fff7e6;
}

.it__tab[aria-selected=true] .it__icon {
  transform: scale(1.18);
}

.it__tab[aria-selected=true] .it__label {
  opacity: 1;
}

.it__tab::before {
  content: "";
  position: absolute;
  top: calc(4px + 11px);
  left: 50%;
  width: 30px;
  height: 30px;
  margin: -15px 0 0 -15px;
  border-radius: 50%;
  background: rgba(255, 247, 230, 0.2);
  filter: blur(2px);
  opacity: 0;
  pointer-events: none;
}

.it.is-demo .it__tab:nth-child(1) .it__icon {
  animation: it-bump 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

.it.is-demo .it__tab:nth-child(2) .it__icon {
  animation: it-bump 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
  animation-delay: -1.3333333333s;
}

.it.is-demo .it__tab:nth-child(3) .it__icon {
  animation: it-bump 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
  animation-delay: -0.6666666667s;
}

@keyframes it-bump {
  0%, 8%, 100% {
    transform: scale(1);
  }
  4% {
    transform: scale(1.18);
  }
}
.it.is-demo .it__tab:nth-child(1)::before {
  animation: it-trail-loop 2s ease-out infinite;
}

.it.is-demo .it__tab:nth-child(2)::before {
  animation: it-trail-loop 2s ease-out infinite;
  animation-delay: -1.3333333333s;
}

.it.is-demo .it__tab:nth-child(3)::before {
  animation: it-trail-loop 2s ease-out infinite;
  animation-delay: -0.6666666667s;
}

@keyframes it-trail-loop {
  0% {
    transform: scale(0.6);
    opacity: 0;
  }
  2% {
    transform: scale(1.1);
    opacity: 0.2;
  }
  6% {
    transform: scale(1.25);
    opacity: 0.16;
  }
  12%, 100% {
    transform: scale(1.6);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .it__icon, .it__label {
    transition: none;
  }
  .it.is-demo .it__tab .it__icon,
  .it.is-demo .it__tab::before {
    animation: none !important;
  }
  .it__tab::before {
    opacity: 0;
  }
}

// role=tablist 의 실제 접근성 패턴: 클릭·좌우 화살표로 aria-selected 와 포커스를 옮긴다 (9줄).
var root = document.querySelector('.it'), tabs = [].slice.call(root.querySelectorAll('[role=tab]'));
function select(i) {
  tabs.forEach(function (t, j) { var on = j === i; t.setAttribute('aria-selected', on); t.tabIndex = on ? 0 : -1; });
  tabs[i].focus({ preventScroll: true }); root.classList.remove('is-demo');
}
tabs.forEach(function (t, i) {
  t.addEventListener('click', function () { select(i); });
  t.addEventListener('keydown', function (e) {
    if (e.key === 'ArrowRight') select((i + 1) % tabs.length);
    else if (e.key === 'ArrowLeft') select((i - 1 + tabs.length) % tabs.length);
  });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./IconTabs.module.scss";

const TABS = [
  { label: "홈", icon: "M4 11 12 4l8 7v8a1 1 0 0 1-1 1h-4v-6H9v6H5a1 1 0 0 1-1-1z" },
  { label: "마이", icon: "M4 21c0-4.4 3.6-7 8-7s8 2.6 8 7" },
];

export type IconTabsProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function IconTabs({ duration = 220, easing = "cubic-bezier(.2,1.4,.4,1)", color = "#fff7e6" }: IconTabsProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const move = (dir: 1 | -1) => setActive((active + dir + TABS.length) % TABS.length);

  return (
    <div className={styles.it} style={vars} role="tablist">
      {TABS.map((t, i) => (
        <button key={t.label} type="button" role="tab" aria-selected={i === active} tabIndex={i === active ? 0 : -1}
                className={styles.tab} onClick={() => setActive(i)}
                onKeyDown={(e: { key: string }) => { if (e.key === "ArrowRight") move(1); if (e.key === "ArrowLeft") move(-1); }}>
          <svg className={styles.icon} viewBox="0 0 24 24" width={22} height={22} aria-hidden="true">
            <path d={t.icon} fill="currentColor" />
          </svg>
          <span className={styles.label}>{t.label}</span>
        </button>
      ))}
    </div>
  );
}

<main class="stage">
  <div class="st is-demo">
    <input type="radio" name="st-tab" id="st-1" class="st__radio" checked>
    <input type="radio" name="st-tab" id="st-2" class="st__radio">
    <input type="radio" name="st-tab" id="st-3" class="st__radio">
    <input type="radio" name="st-tab" id="st-4" class="st__radio">
    <input type="radio" name="st-tab" id="st-5" class="st__radio">
    <div class="st__scroller">
      <div class="st__nav">
        <label class="st__tab" for="st-1">Tất cả</label>
        <label class="st__tab" for="st-2">Quần áo</label>
        <label class="st__tab" for="st-3">Giày</label>
        <label class="st__tab" for="st-4">Túi xách</label>
        <label class="st__tab" for="st-5">Phụ kiện</label>
        <span class="st__trail" aria-hidden="true"></span>
        <span class="st__indicator" aria-hidden="true"></span>
      </div>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;                             // 인디케이터가 미끄러지는 시간
$easing: $ease-lerp-settle;                       // 관성 lerp — 목표를 12.6% 넘겼다가 정착 (2026-09-15 형태 2차 한 겹)
$color: $subject-ink;                             // 인디케이터 색 (노란 무대라 어둡게)

@include stage($stage-yellow);

$tab-w: 88px;   // 탭 다섯 개가 같은 폭이라 인디케이터 이동값을 고정 배수로 쓸 수 있다

.st { width: min(260px, 78vw); }
.st__radio { position: absolute; opacity: 0; pointer-events: none; }

// 다섯 탭(88px × 5 = 440px)이 상자(260px)보다 넓어 가로로 넘친다 — 그래서 스냅 스크롤이 필요하다
.st__scroller {
  overflow-x: auto;
  overflow-y: hidden;
  scroll-snap-type: x mandatory;
  border-radius: $r-sm;
  -webkit-overflow-scrolling: touch;
}
.st__nav {
  position: relative;
  display: flex;
}
// 글자색·굵기는 항상 고정한다 — 밑줄(인디케이터)이 데모 루프에서 :checked 와 다른 탭에 가 있어도
// "이 탭이 진짜 활성" 이라는 잘못된 신호를 안 준다. 활성 신호는 밑줄 위치 하나로만 준다
.st__tab {
  flex: 0 0 $tab-w;
  scroll-snap-align: start;
  text-align: center;
  padding: $sp-3 $sp-1;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 13px);
  line-height: 1;
  font-family: inherit;
  color: $subject-ink;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.st__indicator {
  position: absolute; left: 0; bottom: 0;
  width: $tab-w; height: 3px;
  background: $color;
  border-radius: $r-pill;
  transform: translateX(0);
  transition: transform $duration $easing;
}
// 이동 궤적 트레일 잔상 — 인디케이터와 같은 .st__scroller 안(.st__nav 자식, .st__indicator 형제)에 둬야 st-scroll 로 같이 밀린다
.st__trail {
  position: absolute; left: 0; bottom: 0;
  width: $tab-w; height: 3px;
  background: $color;
  border-radius: $r-pill;
  opacity: .32;
  filter: blur(1.5px);
  transform: translateX(0);
  transition: transform calc($duration * 1.8) ease-out;
}

// ── 실제 동작: :checked 만으로 인디케이터가 옮겨간다 ──────────────
@for $i from 1 through 5 {
  #st-#{$i}:checked ~ .st__scroller .st__indicator { transform: translateX(#{$tab-w * ($i - 1)}); }
  #st-#{$i}:checked ~ .st__scroller .st__trail { transform: translateX(#{$tab-w * ($i - 1)}); }
}

// ── 데모 루프: 다섯 탭을 다 돈다. 상자(260px)엔 세 탭만 들어가므로
// 뒤 두 탭(가방·액세서리)로 갈 땐 .st__nav 자체를 밀어야 "스크롤"이 보인다 —
// 인디케이터만 옮기면 보이지도 않는 탭으로 움직여 아무 일도 안 일어나는 것처럼 보였다
// (사용자 2026-09-10 스크린샷 지적: 06 이 그냥 밑줄 3개 + 빈 공간으로 보임)
.st.is-demo .st__indicator { animation: st-loop $dur-loop $easing infinite; }
.st.is-demo .st__trail { animation: st-loop $dur-loop $easing infinite; animation-delay: calc($dur-loop * .06); } // 6% 위상만큼 늦게 쫓아가 트레일로 읽힌다
.st.is-demo .st__nav { animation: st-scroll $dur-loop $easing infinite; }
@keyframes st-loop {
  0%, 12%  { transform: translateX(0); }
  24%, 32% { transform: translateX(#{$tab-w}); }
  44%, 52% { transform: translateX(#{$tab-w * 2}); }
  64%, 72% { transform: translateX(#{$tab-w * 3}); }
  84%, 92% { transform: translateX(#{$tab-w * 4}); }
  100%     { transform: translateX(0); }
}
// 나머지 탭이 상자 안에 보이도록 탭 스트립 자체를 왼쪽으로 민다 (translateX — scrollLeft 는 WAAPI 로 못 잰다)
@keyframes st-scroll {
  0%, 12%, 24%, 32% { transform: translateX(0); }
  44%, 52%          { transform: translateX(#{-$tab-w}); }
  64%, 92%          { transform: translateX(#{-$tab-w * 2}); }
  100%              { transform: translateX(0); }
}

@media (prefers-reduced-motion: reduce) {
  .st__indicator, .st__trail { transition: none; }
  .st.is-demo .st__indicator, .st.is-demo .st__trail, .st.is-demo .st__nav { animation: none !important; }
  .st__trail { opacity: 0; } // 관성·트레일 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.st {
  width: min(260px, 78vw);
}

.st__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.st__scroller {
  overflow-x: auto;
  overflow-y: hidden;
  scroll-snap-type: x mandatory;
  border-radius: 8px;
  -webkit-overflow-scrolling: touch;
}

.st__nav {
  position: relative;
  display: flex;
}

.st__tab {
  flex: 0 0 88px;
  scroll-snap-align: start;
  text-align: center;
  padding: 12px 4px;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 13px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.st__indicator {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 88px;
  height: 3px;
  background: #17141a;
  border-radius: 999px;
  transform: translateX(0);
  transition: transform 300ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

.st__trail {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 88px;
  height: 3px;
  background: #17141a;
  border-radius: 999px;
  opacity: 0.32;
  filter: blur(1.5px);
  transform: translateX(0);
  transition: transform 540ms ease-out;
}

#st-1:checked ~ .st__scroller .st__indicator {
  transform: translateX(0px);
}

#st-1:checked ~ .st__scroller .st__trail {
  transform: translateX(0px);
}

#st-2:checked ~ .st__scroller .st__indicator {
  transform: translateX(88px);
}

#st-2:checked ~ .st__scroller .st__trail {
  transform: translateX(88px);
}

#st-3:checked ~ .st__scroller .st__indicator {
  transform: translateX(176px);
}

#st-3:checked ~ .st__scroller .st__trail {
  transform: translateX(176px);
}

#st-4:checked ~ .st__scroller .st__indicator {
  transform: translateX(264px);
}

#st-4:checked ~ .st__scroller .st__trail {
  transform: translateX(264px);
}

#st-5:checked ~ .st__scroller .st__indicator {
  transform: translateX(352px);
}

#st-5:checked ~ .st__scroller .st__trail {
  transform: translateX(352px);
}

.st.is-demo .st__indicator {
  animation: st-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

.st.is-demo .st__trail {
  animation: st-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
  animation-delay: 0.12s;
}

.st.is-demo .st__nav {
  animation: st-scroll 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

@keyframes st-loop {
  0%, 12% {
    transform: translateX(0);
  }
  24%, 32% {
    transform: translateX(88px);
  }
  44%, 52% {
    transform: translateX(176px);
  }
  64%, 72% {
    transform: translateX(264px);
  }
  84%, 92% {
    transform: translateX(352px);
  }
  100% {
    transform: translateX(0);
  }
}
@keyframes st-scroll {
  0%, 12%, 24%, 32% {
    transform: translateX(0);
  }
  44%, 52% {
    transform: translateX(-88px);
  }
  64%, 92% {
    transform: translateX(-176px);
  }
  100% {
    transform: translateX(0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .st__indicator, .st__trail {
    transition: none;
  }
  .st.is-demo .st__indicator, .st.is-demo .st__trail, .st.is-demo .st__nav {
    animation: none !important;
  }
  .st__trail {
    opacity: 0;
  }
}

// 스크롤은 브라우저 scroll-snap 이 처리한다. 이동은 :checked 만으로 동작. 실제 클릭이면 데모 루프만 뗀다.
document.querySelectorAll('.st__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.st').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./ScrollTabs.module.scss";

const TABS = ["전체", "의류", "신발", "가방", "액세서리"];
const TAB_W = 88;

export type ScrollTabsProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--i"?: number };

export default function ScrollTabs({ duration = 300, easing = "cubic-bezier(.2,.8,.2,1)", color = "#17141a" }: ScrollTabsProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--i": active };

  return (
    <div className={styles.st} style={vars}>
      <div className={styles.scroller}>
        <div className={styles.nav} role="tablist">
          {TABS.map((t, i) => (
            <button key={t} type="button" role="tab" aria-selected={i === active}
                    className={styles.tab} style={{ flex: `0 0 ${TAB_W}px` }} onClick={() => setActive(i)}>
              {t}
            </button>
          ))}
          <span className={styles.indicator} aria-hidden="true" />
        </div>
      </div>
    </div>
  );
}

<main class="stage">
  <div class="vt is-demo">
    <input type="radio" name="vt-tab" id="vt-1" class="vt__radio" checked>
    <input type="radio" name="vt-tab" id="vt-2" class="vt__radio">
    <input type="radio" name="vt-tab" id="vt-3" class="vt__radio">
    <div class="vt__nav">
      <span class="vt__trail" aria-hidden="true"></span>
      <span class="vt__indicator" aria-hidden="true"></span>
      <label class="vt__tab" for="vt-1">Tài khoản</label>
      <label class="vt__tab" for="vt-2">Thông báo</label>
      <label class="vt__tab" for="vt-3">Bảo mật</label>
    </div>
    <div class="vt__panels">
      <p class="vt__panel vt__panel--1">Đổi tên và email của bạn.</p>
      <p class="vt__panel vt__panel--2">Chọn thông báo đẩy và email.</p>
      <p class="vt__panel vt__panel--3">Quản lý mật khẩu và xác thực hai bước.</p>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;                             // 인디케이터가 위아래로 미끄러지는 시간
$easing: $ease-lerp-settle;                       // 관성 lerp — 목표를 12.6% 넘겼다가 정착 (2026-09-15 형태 2차 한 겹)
$color: $subject-cream;                           // 인디케이터 색

@include stage($stage-orange);

$row-h: 36px;

.vt { display: flex; gap: $sp-6; width: min(280px, 82vw); }
.vt__radio { position: absolute; opacity: 0; pointer-events: none; }

.vt__nav {
  position: relative;
  display: flex;
  flex-direction: column;
  flex: 0 0 auto;
  border-left: 2px solid rgba(255, 247, 230, .18);
  padding-left: $sp-4;
}
.vt__tab {
  height: $row-h;
  display: flex;
  align-items: center;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: rgba($subject-ink, .85);                 // 비활성 탭 — 주황 면 위 4.62:1
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.vt__indicator {
  position: absolute; left: -2px; top: 0;
  width: 2px; height: $row-h;
  background: $color;
  border-radius: $r-xs;
  transform: translateY(0);
  transition: transform $duration $easing;
}
// 이동 궤적 트레일 잔상 — 인디케이터보다 1.8배 느리게 같은 목적지를 쫓아가며 뒤로 흐른다
.vt__trail {
  position: absolute; left: -2px; top: 0;
  width: 2px; height: $row-h;
  background: $color;
  border-radius: $r-xs;
  opacity: .32;
  filter: blur(1.5px);
  transform: translateY(0);
  transition: transform calc($duration * 1.8) ease-out;
}

// ── 실제 동작: :checked 만으로 인디케이터가 세로로 옮겨간다 ──────────────
#vt-1:checked ~ .vt__nav .vt__indicator { transform: translateY(0); }
#vt-2:checked ~ .vt__nav .vt__indicator { transform: translateY(#{$row-h}); }
#vt-3:checked ~ .vt__nav .vt__indicator { transform: translateY(#{$row-h * 2}); }
#vt-1:checked ~ .vt__nav .vt__trail { transform: translateY(0); }
#vt-2:checked ~ .vt__nav .vt__trail { transform: translateY(#{$row-h}); }
#vt-3:checked ~ .vt__nav .vt__trail { transform: translateY(#{$row-h * 2}); }
#vt-1:checked ~ .vt__nav label[for="vt-1"],
#vt-2:checked ~ .vt__nav label[for="vt-2"],
#vt-3:checked ~ .vt__nav label[for="vt-3"] { color: $subject-ink; } // 활성 탭 글자 — 크림은 3.11 로 미달 ($color 인디케이터는 그대로)

// 패널 세 개를 같은 grid 칸에 포개 두면 인디케이터와 함께 바뀌어도 자리가 안 흔들린다
.vt__panels { position: relative; display: grid; flex: 1 1 auto; min-width: 0; }
.vt__panel {
  grid-area: 1 / 1;
  margin: 0;
  color: $subject-ink;                            // 패널 본문 — 5.50:1
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
  opacity: 0;
  transition: opacity $duration $easing;
}
#vt-1:checked ~ .vt__panels .vt__panel--1,
#vt-2:checked ~ .vt__panels .vt__panel--2,
#vt-3:checked ~ .vt__panels .vt__panel--3 { opacity: 1; }

// ── 데모 루프: 클릭 전까지 세 탭을 스스로 오간다 (인디케이터·패널이 같은 박자) ──────────────
.vt.is-demo .vt__indicator { animation: vt-loop $dur-loop $easing infinite; }
.vt.is-demo .vt__trail { animation: vt-loop $dur-loop $easing infinite; animation-delay: calc($dur-loop * .06); } // 6% 위상만큼 늦게 쫓아가 트레일로 읽힌다
.vt.is-demo .vt__panel--1 { animation: vt-panel-1 $dur-loop $easing infinite; }
.vt.is-demo .vt__panel--2 { animation: vt-panel-2 $dur-loop $easing infinite; }
.vt.is-demo .vt__panel--3 { animation: vt-panel-3 $dur-loop $easing infinite; }
@keyframes vt-loop {
  0%, 15%  { transform: translateY(0); }
  33%, 48% { transform: translateY(#{$row-h}); }
  66%, 81% { transform: translateY(#{$row-h * 2}); }
  100%     { transform: translateY(0); }
}
@keyframes vt-panel-1 { 0%, 15% { opacity: 1; } 30%, 100% { opacity: 0; } }
@keyframes vt-panel-2 { 0%, 30% { opacity: 0; } 45%, 63% { opacity: 1; } 78%, 100% { opacity: 0; } }
@keyframes vt-panel-3 { 0%, 63% { opacity: 0; } 78%, 96% { opacity: 1; } 100% { opacity: 0; } }

@media (prefers-reduced-motion: reduce) {
  .vt__indicator, .vt__panel, .vt__trail { transition: none; }
  .vt.is-demo .vt__indicator,
  .vt.is-demo .vt__panel--1,
  .vt.is-demo .vt__panel--2,
  .vt.is-demo .vt__panel--3,
  .vt.is-demo .vt__trail { animation: none !important; }
  .vt__trail { opacity: 0; } // 관성·트레일 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.vt {
  display: flex;
  gap: 24px;
  width: min(280px, 82vw);
}

.vt__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.vt__nav {
  position: relative;
  display: flex;
  flex-direction: column;
  flex: 0 0 auto;
  border-left: 2px solid rgba(255, 247, 230, 0.18);
  padding-left: 16px;
}

.vt__tab {
  height: 36px;
  display: flex;
  align-items: center;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: rgba(23, 20, 26, 0.85);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.vt__indicator {
  position: absolute;
  left: -2px;
  top: 0;
  width: 2px;
  height: 36px;
  background: #fff7e6;
  border-radius: 4px;
  transform: translateY(0);
  transition: transform 300ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

.vt__trail {
  position: absolute;
  left: -2px;
  top: 0;
  width: 2px;
  height: 36px;
  background: #fff7e6;
  border-radius: 4px;
  opacity: 0.32;
  filter: blur(1.5px);
  transform: translateY(0);
  transition: transform 540ms ease-out;
}

#vt-1:checked ~ .vt__nav .vt__indicator {
  transform: translateY(0);
}

#vt-2:checked ~ .vt__nav .vt__indicator {
  transform: translateY(36px);
}

#vt-3:checked ~ .vt__nav .vt__indicator {
  transform: translateY(72px);
}

#vt-1:checked ~ .vt__nav .vt__trail {
  transform: translateY(0);
}

#vt-2:checked ~ .vt__nav .vt__trail {
  transform: translateY(36px);
}

#vt-3:checked ~ .vt__nav .vt__trail {
  transform: translateY(72px);
}

#vt-1:checked ~ .vt__nav label[for=vt-1],
#vt-2:checked ~ .vt__nav label[for=vt-2],
#vt-3:checked ~ .vt__nav label[for=vt-3] {
  color: #17141a;
}

.vt__panels {
  position: relative;
  display: grid;
  flex: 1 1 auto;
  min-width: 0;
}

.vt__panel {
  grid-area: 1/1;
  margin: 0;
  color: #17141a;
  font-weight: 400;
  font-size: clamp(12px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
  opacity: 0;
  transition: opacity 300ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

#vt-1:checked ~ .vt__panels .vt__panel--1,
#vt-2:checked ~ .vt__panels .vt__panel--2,
#vt-3:checked ~ .vt__panels .vt__panel--3 {
  opacity: 1;
}

.vt.is-demo .vt__indicator {
  animation: vt-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

.vt.is-demo .vt__trail {
  animation: vt-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
  animation-delay: 0.12s;
}

.vt.is-demo .vt__panel--1 {
  animation: vt-panel-1 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

.vt.is-demo .vt__panel--2 {
  animation: vt-panel-2 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

.vt.is-demo .vt__panel--3 {
  animation: vt-panel-3 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

@keyframes vt-loop {
  0%, 15% {
    transform: translateY(0);
  }
  33%, 48% {
    transform: translateY(36px);
  }
  66%, 81% {
    transform: translateY(72px);
  }
  100% {
    transform: translateY(0);
  }
}
@keyframes vt-panel-1 {
  0%, 15% {
    opacity: 1;
  }
  30%, 100% {
    opacity: 0;
  }
}
@keyframes vt-panel-2 {
  0%, 30% {
    opacity: 0;
  }
  45%, 63% {
    opacity: 1;
  }
  78%, 100% {
    opacity: 0;
  }
}
@keyframes vt-panel-3 {
  0%, 63% {
    opacity: 0;
  }
  78%, 96% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .vt__indicator, .vt__panel, .vt__trail {
    transition: none;
  }
  .vt.is-demo .vt__indicator,
  .vt.is-demo .vt__panel--1,
  .vt.is-demo .vt__panel--2,
  .vt.is-demo .vt__panel--3,
  .vt.is-demo .vt__trail {
    animation: none !important;
  }
  .vt__trail {
    opacity: 0;
  }
}

// 이동은 :checked 만으로 이미 동작한다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.vt__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.vt').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./VerticalTabs.module.scss";

const TABS = [
  { label: "계정", panel: "이름과 이메일을 바꿉니다." },
  { label: "알림", panel: "푸시·메일 알림을 고릅니다." },
  { label: "보안", panel: "비밀번호와 2단계 인증을 관리합니다." },
];

export type VerticalTabsProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--i"?: number };

export default function VerticalTabs({ duration = 300, easing = "cubic-bezier(.2,.8,.2,1)", color = "#fff7e6" }: VerticalTabsProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--i": active };

  return (
    <div className={styles.vt} style={vars}>
      <div className={styles.nav} role="tablist">
        <span className={styles.indicator} aria-hidden="true" />
        {TABS.map((t, i) => (
          <button key={t.label} type="button" role="tab" aria-selected={i === active}
                  className={styles.tab} onClick={() => setActive(i)}>
            {t.label}
          </button>
        ))}
      </div>
      <p className={styles.panel}>{TABS[active].panel}</p>
    </div>
  );
}

<main class="stage">
  <div class="bt is-demo">
    <input type="radio" name="bt-tab" id="bt-1" class="bt__radio" checked>
    <input type="radio" name="bt-tab" id="bt-2" class="bt__radio">
    <input type="radio" name="bt-tab" id="bt-3" class="bt__radio">
    <div class="bt__nav">
      <label class="bt__tab" for="bt-1"><span class="bt__text">Tất cả</span></label>
      <label class="bt__tab" for="bt-2"><span class="bt__text">Đang xử lý</span></label>
      <label class="bt__tab" for="bt-3"><span class="bt__text">Hoàn tất</span></label>
      <span class="bt__trail" aria-hidden="true"></span>
      <span class="bt__indicator" aria-hidden="true"></span>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-enter;                            // 인디케이터가 튕기며 도착하는 시간
$easing: $ease-lerp-settle;                       // 관성 lerp — 목표를 12.6% 넘겼다가 정착 (2026-09-15 형태 2차 한 겹). 글자 팝(bt-pop)도 같은 곡선을 탄다
$color: $subject-blue-deep;                       // 잉크 글자가 4.03 으로 미달이라 짙은 파랑으로 (크림 글자 5.98:1)

@include stage($stage-paper);

.bt { width: min(300px, 86vw); }
.bt__radio { position: absolute; opacity: 0; pointer-events: none; }

.bt__nav {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding: $sp-1;
  background: rgba(23, 20, 26, .06);
  border-radius: $r-pill;
}
// 글자색의 기본은 잉크다 — 무대(흰색) 위에서 16:1. 알약 위에 온(:checked) 글자만 크림(5.98:1)으로 바뀐다.
// 활성 신호는 알약의 위치와 글자의 튕김이 맡고, 데모 루프에서는 bt-ink-* 가 알약과 같은 박자로 글자색을 옮긴다
.bt__tab {
  position: relative; z-index: 1;
  text-align: center;
  padding: $sp-2 $sp-1;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: $subject-ink;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.bt__text { display: inline-block; transform: scale(1); }
.bt__indicator {
  position: absolute; top: $sp-1; bottom: $sp-1; left: $sp-1;
  width: calc((100% - #{$sp-1} * 2) / 3);
  background: $color;
  border-radius: $r-pill;
  transform: translateX(0);
  transition: transform $duration $easing;
}
// 이동 궤적 트레일 잔상 — 인디케이터보다 1.8배 느리게 같은 목적지를 쫓아가며 뒤로 흐른다
.bt__trail {
  position: absolute; top: $sp-1; bottom: $sp-1; left: $sp-1;
  width: calc((100% - #{$sp-1} * 2) / 3);
  background: $color;
  border-radius: $r-pill;
  opacity: .32;
  filter: blur(1.5px);
  transform: translateX(0);
  transition: transform calc($duration * 1.8) ease-out;
}

// ── 실제 동작: :checked 만으로 인디케이터가 튕기며 옮겨간다 ──────────────
#bt-1:checked ~ .bt__nav .bt__indicator { transform: translateX(0%); }
#bt-2:checked ~ .bt__nav .bt__indicator { transform: translateX(100%); }
#bt-3:checked ~ .bt__nav .bt__indicator { transform: translateX(200%); }
#bt-1:checked ~ .bt__nav .bt__trail { transform: translateX(0%); }
#bt-2:checked ~ .bt__nav .bt__trail { transform: translateX(100%); }
#bt-3:checked ~ .bt__nav .bt__trail { transform: translateX(200%); }
// 알약 위에 온 글자만 크림 — 잉크를 그대로 두면 짙은 파랑 위 2.87:1 이다
#bt-1:checked ~ .bt__nav label[for="bt-1"],
#bt-2:checked ~ .bt__nav label[for="bt-2"],
#bt-3:checked ~ .bt__nav label[for="bt-3"] { color: $subject-cream; }
// 실제 클릭으로 :checked 가 바뀔 때만 그 글자가 한 번 튕긴다
#bt-1:checked ~ .bt__nav label[for="bt-1"] .bt__text,
#bt-2:checked ~ .bt__nav label[for="bt-2"] .bt__text,
#bt-3:checked ~ .bt__nav label[for="bt-3"] .bt__text { animation: bt-pop 400ms $easing; }
@keyframes bt-pop { 0% { transform: scale(1); } 55% { transform: scale(1.18); } 100% { transform: scale(1); } }

// ── 데모 루프: 클릭 전까지 인디케이터와 글자가 같은 박자로 세 탭을 오간다 ──────────────
.bt.is-demo .bt__indicator { animation: bt-loop $dur-loop $easing infinite; }
.bt.is-demo .bt__trail { animation: bt-loop $dur-loop $easing infinite; animation-delay: calc($dur-loop * .06); } // 6% 위상만큼 늦게 쫓아가 트레일로 읽힌다
.bt.is-demo .bt__nav label:nth-child(1) .bt__text { animation: bt-pop-1 $dur-loop $easing infinite, bt-ink-1 $dur-loop linear infinite; }
.bt.is-demo .bt__nav label:nth-child(2) .bt__text { animation: bt-pop-2 $dur-loop $easing infinite, bt-ink-2 $dur-loop linear infinite; }
.bt.is-demo .bt__nav label:nth-child(3) .bt__text { animation: bt-pop-3 $dur-loop $easing infinite, bt-ink-3 $dur-loop linear infinite; }
// 글자색도 알약과 같은 박자(0·15/33·48/66·81/100%)로 — 크림 글자가 알약 없는 자리에 남지 않게
@keyframes bt-ink-1 { 0%, 15% { color: $subject-cream; } 23%, 87% { color: $subject-ink; } 95%, 100% { color: $subject-cream; } }
@keyframes bt-ink-2 { 0%, 25% { color: $subject-ink; } 33%, 48% { color: $subject-cream; } 56%, 100% { color: $subject-ink; } }
@keyframes bt-ink-3 { 0%, 58% { color: $subject-ink; } 66%, 81% { color: $subject-cream; } 89%, 100% { color: $subject-ink; } }
@keyframes bt-loop {
  0%, 15%  { transform: translateX(0%); }
  33%, 48% { transform: translateX(100%); }
  66%, 81% { transform: translateX(200%); }
  100%     { transform: translateX(0%); }
}
// 인디케이터가 도착하는 지점(15%·48%·81%·100%→0%)에서 그 탭 글자만 튕긴다
@keyframes bt-pop-1 { 0%, 100% { transform: scale(1.18); } 5%, 96% { transform: scale(1); } }
@keyframes bt-pop-2 { 0%, 43%, 100% { transform: scale(1); } 48% { transform: scale(1.18); } 53% { transform: scale(1); } }
@keyframes bt-pop-3 { 0%, 76%, 100% { transform: scale(1); } 81% { transform: scale(1.18); } 86% { transform: scale(1); } }

@media (prefers-reduced-motion: reduce) {
  .bt__indicator, .bt__text, .bt__trail { transition: none; animation: none !important; }
  .bt.is-demo .bt__indicator, .bt.is-demo .bt__text, .bt.is-demo .bt__trail { animation: none !important; }
  .bt__trail { opacity: 0; } // 관성·트레일 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.bt {
  width: min(300px, 86vw);
}

.bt__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.bt__nav {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding: 4px;
  background: rgba(23, 20, 26, 0.06);
  border-radius: 999px;
}

.bt__tab {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 8px 4px;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.bt__text {
  display: inline-block;
  transform: scale(1);
}

.bt__indicator {
  position: absolute;
  top: 4px;
  bottom: 4px;
  left: 4px;
  width: calc((100% - 4px * 2) / 3);
  background: #0a4fe8;
  border-radius: 999px;
  transform: translateX(0);
  transition: transform 600ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

.bt__trail {
  position: absolute;
  top: 4px;
  bottom: 4px;
  left: 4px;
  width: calc((100% - 4px * 2) / 3);
  background: #0a4fe8;
  border-radius: 999px;
  opacity: 0.32;
  filter: blur(1.5px);
  transform: translateX(0);
  transition: transform 1080ms ease-out;
}

#bt-1:checked ~ .bt__nav .bt__indicator {
  transform: translateX(0%);
}

#bt-2:checked ~ .bt__nav .bt__indicator {
  transform: translateX(100%);
}

#bt-3:checked ~ .bt__nav .bt__indicator {
  transform: translateX(200%);
}

#bt-1:checked ~ .bt__nav .bt__trail {
  transform: translateX(0%);
}

#bt-2:checked ~ .bt__nav .bt__trail {
  transform: translateX(100%);
}

#bt-3:checked ~ .bt__nav .bt__trail {
  transform: translateX(200%);
}

#bt-1:checked ~ .bt__nav label[for=bt-1],
#bt-2:checked ~ .bt__nav label[for=bt-2],
#bt-3:checked ~ .bt__nav label[for=bt-3] {
  color: #fff7e6;
}

#bt-1:checked ~ .bt__nav label[for=bt-1] .bt__text,
#bt-2:checked ~ .bt__nav label[for=bt-2] .bt__text,
#bt-3:checked ~ .bt__nav label[for=bt-3] .bt__text {
  animation: bt-pop 400ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

@keyframes bt-pop {
  0% {
    transform: scale(1);
  }
  55% {
    transform: scale(1.18);
  }
  100% {
    transform: scale(1);
  }
}
.bt.is-demo .bt__indicator {
  animation: bt-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

.bt.is-demo .bt__trail {
  animation: bt-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
  animation-delay: 0.12s;
}

.bt.is-demo .bt__nav label:nth-child(1) .bt__text {
  animation: bt-pop-1 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite, bt-ink-1 2s linear infinite;
}

.bt.is-demo .bt__nav label:nth-child(2) .bt__text {
  animation: bt-pop-2 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite, bt-ink-2 2s linear infinite;
}

.bt.is-demo .bt__nav label:nth-child(3) .bt__text {
  animation: bt-pop-3 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite, bt-ink-3 2s linear infinite;
}

@keyframes bt-ink-1 {
  0%, 15% {
    color: #fff7e6;
  }
  23%, 87% {
    color: #17141a;
  }
  95%, 100% {
    color: #fff7e6;
  }
}
@keyframes bt-ink-2 {
  0%, 25% {
    color: #17141a;
  }
  33%, 48% {
    color: #fff7e6;
  }
  56%, 100% {
    color: #17141a;
  }
}
@keyframes bt-ink-3 {
  0%, 58% {
    color: #17141a;
  }
  66%, 81% {
    color: #fff7e6;
  }
  89%, 100% {
    color: #17141a;
  }
}
@keyframes bt-loop {
  0%, 15% {
    transform: translateX(0%);
  }
  33%, 48% {
    transform: translateX(100%);
  }
  66%, 81% {
    transform: translateX(200%);
  }
  100% {
    transform: translateX(0%);
  }
}
@keyframes bt-pop-1 {
  0%, 100% {
    transform: scale(1.18);
  }
  5%, 96% {
    transform: scale(1);
  }
}
@keyframes bt-pop-2 {
  0%, 43%, 100% {
    transform: scale(1);
  }
  48% {
    transform: scale(1.18);
  }
  53% {
    transform: scale(1);
  }
}
@keyframes bt-pop-3 {
  0%, 76%, 100% {
    transform: scale(1);
  }
  81% {
    transform: scale(1.18);
  }
  86% {
    transform: scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .bt__indicator, .bt__text, .bt__trail {
    transition: none;
    animation: none !important;
  }
  .bt.is-demo .bt__indicator, .bt.is-demo .bt__text, .bt.is-demo .bt__trail {
    animation: none !important;
  }
  .bt__trail {
    opacity: 0;
  }
}

// 이동은 :checked 만으로 이미 동작한다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.bt__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.bt').classList.remove('is-demo'); });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./BounceTab.module.scss";

const TABS = ["전체", "진행중", "완료"];

export type BounceTabProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--i"?: number };

export default function BounceTab({ duration = 600, easing = "cubic-bezier(.2,1.4,.4,1)", color = "#0a4fe8" }: BounceTabProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--i": active };

  return (
    <div className={styles.bt} style={vars}>
      <div className={styles.nav} role="tablist">
        {TABS.map((t, i) => (
          <button key={t} type="button" role="tab" aria-selected={i === active}
                  className={styles.tab} onClick={() => setActive(i)}>
            <span key={i === active ? "on" : "off"} className={styles.text}>{t}</span>
          </button>
        ))}
        <span className={styles.indicator} aria-hidden="true" />
      </div>
    </div>
  );
}

<main class="stage">
  <div class="cb is-demo" role="tablist" aria-label="Hộp thư">
    <button class="cb__tab" type="button" role="tab" aria-selected="true" tabindex="0">
      Hộp thư đến <span class="cb__badge">12</span>
    </button>
    <button class="cb__tab" type="button" role="tab" aria-selected="false" tabindex="-1">
      Lưu trữ <span class="cb__badge">3</span>
    </button>
    <button class="cb__tab" type="button" role="tab" aria-selected="false" tabindex="-1">
      Thư rác <span class="cb__badge">1</span>
    </button>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-instant;                          // 배지가 튀어 오르는 시간
$easing: $ease-lerp-settle;                       // 관성 lerp — 목표를 12.6% 넘겼다가 정착 (2026-09-15 형태 2차 한 겹)
$color: $subject-blue-deep;                       // 배지 색 (크림 글자가 얹히므로 진한 파랑)

@include stage($stage-ink);

.cb {
  display: flex;
  gap: $sp-2;
  padding: $sp-2;
  border-radius: $r-card;
  background: rgba(255, 255, 255, .06);
}
.cb__tab {
  border: 0;
  border-radius: $r-control;
  padding: $sp-2 $sp-3;
  background: none;
  color: $subject-cream;                          // 배지(짙은 파랑) 위 5.98:1 · 카드 면 위 14.7:1 — .55 는 2.79 로 미달
  font-weight: 600;
  font-size: clamp(11px, 3vw, 13px);
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.cb__tab[aria-selected="true"] { color: $subject-cream; background: rgba(255, 255, 255, .1); }
.cb__badge {
  position: relative;                             // ::before 잔광 고리의 기준점 (2026-09-15 형태 2차)
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: $sp-5;
  height: $sp-5;
  padding: 0 $sp-1;
  border-radius: $r-pill;
  background: $color;
  color: $subject-cream;
  font-weight: 700;
  font-size: clamp(10px, 2.6vw, 11px);
  line-height: 1;
  font-family: inherit;
  transform: scale(1);
  transition: transform $duration $easing;
}
// 스케일 트레일 잔상 — 배지가 튀어오를 때 뒤로 번지는 원형 잔광 고리 (장식, aria 없는 가상요소라 스크린리더 무관)
.cb__badge::before {
  content: "";
  position: absolute; inset: -3px;
  border-radius: $r-pill;
  background: $color;
  opacity: 0;
  pointer-events: none;
}
.cb__tab[aria-selected="true"] .cb__badge::before { animation: cb-ring $duration ease-out; }
@keyframes cb-ring { 0% { transform: scale(.8); opacity: .4; } 100% { transform: scale(1.7); opacity: 0; } }
.cb__tab[aria-selected="true"] .cb__badge { animation: cb-pop $duration $easing; }
@keyframes cb-pop { 0% { transform: scale(1); } 55% { transform: scale(1.35); } 100% { transform: scale(1); } }

// ── 데모 루프: 클릭 전까지 배지를 하나씩 순서대로 튕긴다 ──────────────
.cb.is-demo .cb__tab:nth-child(1) .cb__badge { animation: cb-loop $dur-loop $easing infinite; }
.cb.is-demo .cb__tab:nth-child(2) .cb__badge { animation: cb-loop $dur-loop $easing infinite; animation-delay: calc($dur-loop / 3 * -2); }
.cb.is-demo .cb__tab:nth-child(3) .cb__badge { animation: cb-loop $dur-loop $easing infinite; animation-delay: calc($dur-loop / 3 * -1); }
// 잔광 고리도 같은 박자·같은 nth-child 딜레이로 순서대로 번진다
.cb.is-demo .cb__tab:nth-child(1) .cb__badge::before { animation: cb-ring $dur-loop ease-out infinite; }
.cb.is-demo .cb__tab:nth-child(2) .cb__badge::before { animation: cb-ring $dur-loop ease-out infinite; animation-delay: calc($dur-loop / 3 * -2); }
.cb.is-demo .cb__tab:nth-child(3) .cb__badge::before { animation: cb-ring $dur-loop ease-out infinite; animation-delay: calc($dur-loop / 3 * -1); }
@keyframes cb-loop {
  0%, 8%, 100% { transform: scale(1); }
  4%           { transform: scale(1.35); }
}

@media (prefers-reduced-motion: reduce) {
  .cb__badge { transition: none; }
  .cb__tab[aria-selected="true"] .cb__badge { animation: none !important; }
  .cb.is-demo .cb__tab .cb__badge { animation: none !important; }
  .cb__badge::before, .cb__tab[aria-selected="true"] .cb__badge::before,
  .cb.is-demo .cb__tab .cb__badge::before { animation: none !important; opacity: 0; } // 잔광 한 겹은 reduced-motion 에서 완전히 꺼진다
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cb {
  display: flex;
  gap: 8px;
  padding: 8px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.06);
}

.cb__tab {
  border: 0;
  border-radius: 12px;
  padding: 8px 12px;
  background: none;
  color: #fff7e6;
  font-weight: 600;
  font-size: clamp(11px, 3vw, 13px);
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.cb__tab[aria-selected=true] {
  color: #fff7e6;
  background: rgba(255, 255, 255, 0.1);
}

.cb__badge {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 20px;
  height: 20px;
  padding: 0 4px;
  border-radius: 999px;
  background: #0a4fe8;
  color: #fff7e6;
  font-weight: 700;
  font-size: clamp(10px, 2.6vw, 11px);
  line-height: 1;
  font-family: inherit;
  transform: scale(1);
  transition: transform 140ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

.cb__badge::before {
  content: "";
  position: absolute;
  inset: -3px;
  border-radius: 999px;
  background: #0a4fe8;
  opacity: 0;
  pointer-events: none;
}

.cb__tab[aria-selected=true] .cb__badge::before {
  animation: cb-ring 140ms ease-out;
}

@keyframes cb-ring {
  0% {
    transform: scale(0.8);
    opacity: 0.4;
  }
  100% {
    transform: scale(1.7);
    opacity: 0;
  }
}
.cb__tab[aria-selected=true] .cb__badge {
  animation: cb-pop 140ms linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1);
}

@keyframes cb-pop {
  0% {
    transform: scale(1);
  }
  55% {
    transform: scale(1.35);
  }
  100% {
    transform: scale(1);
  }
}
.cb.is-demo .cb__tab:nth-child(1) .cb__badge {
  animation: cb-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
}

.cb.is-demo .cb__tab:nth-child(2) .cb__badge {
  animation: cb-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
  animation-delay: -1.3333333333s;
}

.cb.is-demo .cb__tab:nth-child(3) .cb__badge {
  animation: cb-loop 2s linear(0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1) infinite;
  animation-delay: -0.6666666667s;
}

.cb.is-demo .cb__tab:nth-child(1) .cb__badge::before {
  animation: cb-ring 2s ease-out infinite;
}

.cb.is-demo .cb__tab:nth-child(2) .cb__badge::before {
  animation: cb-ring 2s ease-out infinite;
  animation-delay: -1.3333333333s;
}

.cb.is-demo .cb__tab:nth-child(3) .cb__badge::before {
  animation: cb-ring 2s ease-out infinite;
  animation-delay: -0.6666666667s;
}

@keyframes cb-loop {
  0%, 8%, 100% {
    transform: scale(1);
  }
  4% {
    transform: scale(1.35);
  }
}
@media (prefers-reduced-motion: reduce) {
  .cb__badge {
    transition: none;
  }
  .cb__tab[aria-selected=true] .cb__badge {
    animation: none !important;
  }
  .cb.is-demo .cb__tab .cb__badge {
    animation: none !important;
  }
  .cb__badge::before, .cb__tab[aria-selected=true] .cb__badge::before,
  .cb.is-demo .cb__tab .cb__badge::before {
    animation: none !important;
    opacity: 0;
  }
}

// role=tablist 의 실제 접근성 패턴: 클릭·좌우 화살표로 aria-selected 와 포커스를 옮긴다 (9줄).
var root = document.querySelector('.cb'), tabs = [].slice.call(root.querySelectorAll('[role=tab]'));
function select(i) {
  tabs.forEach(function (t, j) { var on = j === i; t.setAttribute('aria-selected', on); t.tabIndex = on ? 0 : -1; });
  tabs[i].focus({ preventScroll: true }); root.classList.remove('is-demo');
}
tabs.forEach(function (t, i) {
  t.addEventListener('click', function () { select(i); });
  t.addEventListener('keydown', function (e) {
    if (e.key === 'ArrowRight') select((i + 1) % tabs.length);
    else if (e.key === 'ArrowLeft') select((i - 1 + tabs.length) % tabs.length);
  });
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./CountBadge.module.scss";

const TABS = [
  { label: "받은편지함", count: 12 },
  { label: "보관", count: 3 },
  { label: "스팸", count: 1 },
];

export type CountBadgeProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function CountBadge({ duration = 140, easing = "cubic-bezier(.2,1.4,.4,1)", color = "#0a4fe8" }: CountBadgeProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const move = (dir: 1 | -1) => setActive((active + dir + TABS.length) % TABS.length);

  return (
    <div className={styles.cb} style={vars} role="tablist">
      {TABS.map((t, i) => (
        <button key={t.label} type="button" role="tab" aria-selected={i === active} tabIndex={i === active ? 0 : -1}
                className={styles.tab} onClick={() => setActive(i)}
                onKeyDown={(e: { key: string }) => { if (e.key === "ArrowRight") move(1); if (e.key === "ArrowLeft") move(-1); }}>
          {t.label} <span key={i === active ? "on" : "off"} className={styles.badge}>{t.count}</span>
        </button>
      ))}
    </div>
  );
}