06data-state 기반 애니메이션(shadcn)

<main class="stage">
  <div class="acc">
    <button class="acc__trigger" type="button" aria-expanded="false">배송 안내</button>
    <div class="acc__panel is-demo" data-state="closed">
      <p>결제 후 1~2일 안에 출고되고, 도서산간은 하루 더 걸립니다.</p>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: 220ms;
$easing: ease-out;
$color: $subject-ink;

// ── 데모 무대 ──────────────────────────────────────────
@include stage($stage-yellow);

.acc {
  box-sizing: border-box;
  width: min(280px, 88vw);
}

.acc__trigger {
  width: 100%;
  padding: $sp-4 $sp-5;
  border: 0;
  border-radius: $r-control;
  background: $color;
  color: $subject-cream;
  font-weight: 700;
  font-size: clamp(14px, 4vw, 16px);
  line-height: 1;
  font-family: inherit;
  text-align: left;
  cursor: pointer;
}

.acc__panel {
  margin-top: $sp-2;
  padding: $sp-4 $sp-5;
  border-radius: $r-control;
  background: rgba($subject-ink, .06);
  transform-origin: top center; // 규칙8: 패널 윗변에서 펼쳐짐
  transform: scaleY(0);
  opacity: 0;
  transition: transform $duration $easing, opacity $duration $easing;

  p { margin: 0; color: $subject-ink; font-weight: 400; font-size: clamp(13px, 3.6vw, 14px); line-height: 1.5; font-family: inherit; }
}

// 실사용: [data-state=open] 만 보고 움직인다. width/height 는 건드리지 않는다
.acc__panel[data-state="open"] {
  transform: scaleY(1);
  opacity: 1;
}

// 데모: transition 은 getAnimations() 에 안 잡혀 렌더 시계로 못 잰다 (blog-demo 실패시표) —
// is-demo 는 같은 모양을 @keyframes 로 2초마다 반복해 측정 가능하게 만든다
.acc__panel.is-demo {
  animation: acc-loop 2s $easing infinite;
}

@keyframes acc-loop {
  0%, 8%   { transform: scaleY(0); opacity: 0; }
  35%, 65% { transform: scaleY(1); opacity: 1; }
  92%, 100% { transform: scaleY(0); opacity: 0; }
}

// ── 접근성 ──────────────────────────────────────────
@media (prefers-reduced-motion: reduce) {
  .acc__panel { transition: opacity $duration linear; transform: none; animation: none; }
  .acc__panel[data-state="closed"] { opacity: 0; }
}

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);
}

.acc {
  box-sizing: border-box;
  width: min(280px, 88vw);
}

.acc__trigger {
  width: 100%;
  padding: 16px 20px;
  border: 0;
  border-radius: 12px;
  background: #17141a;
  color: #fff7e6;
  font-weight: 700;
  font-size: clamp(14px, 4vw, 16px);
  line-height: 1;
  font-family: inherit;
  text-align: left;
  cursor: pointer;
}

.acc__panel {
  margin-top: 8px;
  padding: 16px 20px;
  border-radius: 12px;
  background: rgba(23, 20, 26, 0.06);
  transform-origin: top center;
  transform: scaleY(0);
  opacity: 0;
  transition: transform 220ms ease-out, opacity 220ms ease-out;
}
.acc__panel p {
  margin: 0;
  color: #17141a;
  font-weight: 400;
  font-size: clamp(13px, 3.6vw, 14px);
  line-height: 1.5;
  font-family: inherit;
}

.acc__panel[data-state=open] {
  transform: scaleY(1);
  opacity: 1;
}

.acc__panel.is-demo {
  animation: acc-loop 2s ease-out infinite;
}

@keyframes acc-loop {
  0%, 8% {
    transform: scaleY(0);
    opacity: 0;
  }
  35%, 65% {
    transform: scaleY(1);
    opacity: 1;
  }
  92%, 100% {
    transform: scaleY(0);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .acc__panel {
    transition: opacity 220ms linear;
    transform: none;
    animation: none;
  }
  .acc__panel[data-state=closed] {
    opacity: 0;
  }
}

// data-state 를 토글하는 최소 로직. CSS 가 [data-state=open] 을 보고 움직인다.
var t = document.querySelector('.acc__trigger');
var p = document.querySelector('.acc__panel');
function toggle() {
  var open = p.getAttribute('data-state') === 'open';
  p.setAttribute('data-state', open ? 'closed' : 'open');
  t.setAttribute('aria-expanded', String(!open));
}
t.addEventListener('click', toggle); // 실사용: 클릭마다 data-state 토글 (데모 루프는 .is-demo 키프레임)

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

export type DataStateAccordionProps = {
  trigger?: string;
  children?: string;
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function DataStateAccordion({
  trigger = "Shipping info",
  children = "Ships within 1-2 days of payment; remote areas take one extra day.",
  duration = 220,
  easing = "ease-out",
  color = "#17141a",
}: DataStateAccordionProps) {
  const [open, setOpen] = useState(false);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={styles.acc} style={vars}>
      <button
        type="button"
        className={styles.acc__trigger}
        aria-expanded={open}
        onClick={() => setOpen((v) => !v)}
      >
        {trigger}
      </button>
      <div className={styles.acc__panel} data-state={open ? "open" : "closed"}>
        <p>{children}</p>
      </div>
    </div>
  );
}