07Glass tab

<main class="stage">
  <div class="gt is-demo">
    <input type="radio" name="gt-tab" id="gt-1" class="gt__radio" checked>
    <input type="radio" name="gt-tab" id="gt-2" class="gt__radio">
    <input type="radio" name="gt-tab" id="gt-3" class="gt__radio">
    <div class="gt__nav">
      <span class="gt__pill" aria-hidden="true"></span>
      <label class="gt__tab" for="gt-1">Day</label>
      <label class="gt__tab" for="gt-2">Week</label>
      <label class="gt__tab" for="gt-3">Month</label>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-quick;
$easing: $ease-pop;
$color: $subject-blue;

@include stage($stage-orange);

// 탭 폭을 고정값으로 둔다 — flex:0 0 auto(내용 폭)와 같이 써야 translateX 상수와 어긋나지 않는다 (BD19)
$w: 68px;

.gt { width: min(240px, 82vw); }
.gt__radio { position: absolute; opacity: 0; pointer-events: none; }

.gt__nav {
  position: relative;
  display: flex;
  gap: $sp-2;
  padding: $sp-1;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .14);
  border: 1px solid rgba(255, 255, 255, .3);
  backdrop-filter: blur(12px) saturate(160%);
  -webkit-backdrop-filter: blur(12px) saturate(160%);
}
.gt__tab {
  position: relative;
  z-index: 1;
  flex: 0 0 auto;
  box-sizing: border-box;
  width: $w;
  text-align: center;
  padding: $sp-2 0;
  font: 600 clamp(11px, 3.2vw, 13px)/1 -apple-system, "Segoe UI", sans-serif;
  color: $subject-ink;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.gt__pill {
  position: absolute;
  top: $sp-1; left: $sp-1; bottom: $sp-1;
  box-sizing: border-box;
  width: $w;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .6);
  backdrop-filter: blur(6px);
  box-shadow: $shadow-press;
  transform: translateX(0);
  transition: transform $duration $easing;
}

// 실사용: :checked 만으로 인디케이터가 이동한다
#gt-1:checked ~ .gt__nav .gt__pill { transform: translateX(0); }
#gt-2:checked ~ .gt__nav .gt__pill { transform: translateX(calc(#{$w} + #{$sp-2})); }
#gt-3:checked ~ .gt__nav .gt__pill { transform: translateX(calc((#{$w} + #{$sp-2}) * 2)); }

// 데모 루프: 클릭 전까지 세 자리를 스스로 오간다
.gt.is-demo .gt__pill { animation: gt-loop $dur-loop $easing infinite; }
@keyframes gt-loop {
  0%, 15%  { transform: translateX(0); }
  33%, 48% { transform: translateX(calc(#{$w} + #{$sp-2})); }
  66%, 81% { transform: translateX(calc((#{$w} + #{$sp-2}) * 2)); }
  100%     { transform: translateX(0); }
}

@media (prefers-reduced-motion: reduce) {
  .gt__pill { transition: none; }
  .gt.is-demo .gt__pill { 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);
}

.gt {
  width: min(240px, 82vw);
}

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

.gt__nav {
  position: relative;
  display: flex;
  gap: 8px;
  padding: 4px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.14);
  border: 1px solid rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(12px) saturate(160%);
  -webkit-backdrop-filter: blur(12px) saturate(160%);
}

.gt__tab {
  position: relative;
  z-index: 1;
  flex: 0 0 auto;
  box-sizing: border-box;
  width: 68px;
  text-align: center;
  padding: 8px 0;
  font: 600 clamp(11px, 3.2vw, 13px)/1 -apple-system, "Segoe UI", sans-serif;
  color: #17141a;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.gt__pill {
  position: absolute;
  top: 4px;
  left: 4px;
  bottom: 4px;
  box-sizing: border-box;
  width: 68px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(6px);
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  transform: translateX(0);
  transition: transform 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}

#gt-1:checked ~ .gt__nav .gt__pill {
  transform: translateX(0);
}

#gt-2:checked ~ .gt__nav .gt__pill {
  transform: translateX(calc(68px + 8px));
}

#gt-3:checked ~ .gt__nav .gt__pill {
  transform: translateX(calc((68px + 8px) * 2));
}

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

@keyframes gt-loop {
  0%, 15% {
    transform: translateX(0);
  }
  33%, 48% {
    transform: translateX(calc(68px + 8px));
  }
  66%, 81% {
    transform: translateX(calc((68px + 8px) * 2));
  }
  100% {
    transform: translateX(0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .gt__pill {
    transition: none;
  }
  .gt.is-demo .gt__pill {
    animation: none !important;
  }
}

// 인디케이터는 :checked 만으로 이동한다. 실제 클릭이 오면 데모 루프(.is-demo)만 뗀다.
document.querySelectorAll('.gt__radio').forEach(function (r) {
  r.addEventListener('pointerdown', function () { document.querySelector('.gt').classList.remove('is-demo'); });
});

import { CSSProperties, useState } from "react";
import styles from "./GlassTab.module.scss";

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

export interface GlassTabProps {
  duration?: string;
  easing?: string;
}

const TABS = ["Day", "Week", "Month"];
const TAB_WIDTH = 68;
const GAP = 8;

export default function GlassTab({
  duration = "220ms",
  easing = "cubic-bezier(.2, 1.4, .4, 1)",
}: GlassTabProps) {
  const [active, setActive] = useState(0);
  const style: Vars = {
    "--duration": duration,
    "--easing": easing,
    "--x": `${active * (TAB_WIDTH + GAP)}px`,
  };

  return (
    <div className={styles.wrap} style={style}>
      <div className={styles.nav}>
        <span className={styles.pill} aria-hidden="true" />
        {TABS.map((label, i) => (
          <button
            key={label}
            type="button"
            className={styles.tab}
            aria-pressed={active === i}
            onClick={() => setActive(i)}
          >
            {label}
          </button>
        ))}
      </div>
    </div>
  );
}