07Vertical tabs

<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">Account</label>
      <label class="vt__tab" for="vt-2">Notifications</label>
      <label class="vt__tab" for="vt-3">Security</label>
    </div>
    <div class="vt__panels">
      <p class="vt__panel vt__panel--1">Change your name and email.</p>
      <p class="vt__panel vt__panel--2">Choose push and email notifications.</p>
      <p class="vt__panel vt__panel--3">Manage your password and two-factor authentication.</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>
  );
}