07階層移動のアニメーション

<main class="stage">
  <div class="st is-demo" id="st">
    <div class="st__rail">
      <nav class="st__nav" aria-label="パンくずリスト">
        <ol class="st__list" id="st-list">
          <li class="st__item"><a class="st__link" href="#" data-i="0"><svg viewBox="0 0 256 256" width="14" height="14" aria-hidden="true"><g fill="currentColor"><path d="M216 120v96h-64v-64h-48v64H40v-96a8 8 0 0 1 2.34-5.66l80-80a8 8 0 0 1 11.32 0l80 80A8 8 0 0 1 216 120" opacity=".2"/><path d="m219.31 108.68l-80-80a16 16 0 0 0-22.62 0l-80 80A15.87 15.87 0 0 0 32 120v96a8 8 0 0 0 8 8h64a8 8 0 0 0 8-8v-56h32v56a8 8 0 0 0 8 8h64a8 8 0 0 0 8-8v-96a15.87 15.87 0 0 0-4.69-11.32M208 208h-48v-56a8 8 0 0 0-8-8h-48a8 8 0 0 0-8 8v56H48v-88l80-80l80 80Z"/></g></svg>ホーム</a></li>
          <li class="st__item"><span class="st__sep" aria-hidden="true"><svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m176 128l-80 80V48Z" opacity=".2"/><path d="m181.66 122.34l-80-80A8 8 0 0 0 88 48v160a8 8 0 0 0 13.66 5.66l80-80a8 8 0 0 0 0-11.32M104 188.69V67.31L164.69 128Z"/></g></svg></span><a class="st__link" href="#" data-i="1">ドキュメント</a></li>
          <li class="st__item"><span class="st__sep" aria-hidden="true"><svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m176 128l-80 80V48Z" opacity=".2"/><path d="m181.66 122.34l-80-80A8 8 0 0 0 88 48v160a8 8 0 0 0 13.66 5.66l80-80a8 8 0 0 0 0-11.32M104 188.69V67.31L164.69 128Z"/></g></svg></span><a class="st__link" href="#" data-i="2">2026</a></li>
          <li class="st__item"><span class="st__sep" aria-hidden="true"><svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m176 128l-80 80V48Z" opacity=".2"/><path d="m181.66 122.34l-80-80A8 8 0 0 0 88 48v160a8 8 0 0 0 13.66 5.66l80-80a8 8 0 0 0 0-11.32M104 188.69V67.31L164.69 128Z"/></g></svg></span><a class="st__link" href="#" data-i="3">9月</a></li>
          <li class="st__item"><span class="st__sep" aria-hidden="true"><svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m176 128l-80 80V48Z" opacity=".2"/><path d="m181.66 122.34l-80-80A8 8 0 0 0 88 48v160a8 8 0 0 0 13.66 5.66l80-80a8 8 0 0 0 0-11.32M104 188.69V67.31L164.69 128Z"/></g></svg></span><span class="st__link st__link--now" aria-current="page">請求書</span></li>
        </ol>
      </nav>
    </div>
    <div class="st__btns">
      <button class="st__btn" type="button" id="st-up">上へ</button>
      <button class="st__btn st__btn--ghost" type="button" id="st-down">下へ戻る</button>
    </div>
  </div>
</main>

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

$duration: $dur-base;
$easing: $ease-spring;
$color: $subject-cream;

@include stage($stage-orange);

.st {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  width: 100%;
  max-width: 392px;
}

// 슬라이드 아웃이 문서 폭·높이를 늘리지 않게 — 고정 높이 + overflow:hidden (247 실측)
.st__rail {
  box-sizing: border-box;
  width: 100%;
  height: 48px;
  overflow: hidden;
  display: flex;
  align-items: center;
  padding: 0 $sp-2;
  border-radius: $r-card;
  background: rgba($subject-ink, .92);
}
.st__nav { width: 100%; }
.st__list {
  display: flex;
  align-items: center;
  flex-wrap: nowrap;
  gap: $sp-1;
  margin: 0;
  padding: 0;
  list-style: none;
}
.st__item {
  display: flex;
  align-items: center;
  gap: $sp-1;
  flex: 0 0 auto;
}
.st__item[hidden] { display: none; }
.st__sep {
  display: inline-flex;
  flex: none;
  color: rgba($subject-cream, .45);
}
.st__link {
  display: inline-flex;
  align-items: center;
  gap: $sp-1;
  padding: $sp-1 $sp-2;
  border-radius: $r-pill;
  background: rgba($subject-cream, .18);
  color: $color;
  font-size: 13px;
  line-height: 18px;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  // 이징을 토큰 말고 값으로도 한 번 — 칩 `cubic-bezier` 대조용
  transition: transform $duration cubic-bezier(.2, .8, .2, 1), background $duration $easing;
}
.st__link svg { flex: none; }
.st__link:hover { background: rgba($subject-cream, .34); transform: translateY(-1px); }
.st__link:focus-visible { outline: 2px solid $subject-cream; outline-offset: 2px; }
.st__link--now {
  background: $subject-cream;
  color: $subject-ink;
  font-weight: 700;
  cursor: default;
}

.st__btns { display: flex; gap: $sp-2; }
.st__btn {
  padding: $sp-1 $sp-3;
  border: 0;
  border-radius: $r-pill;
  background: $subject-cream;
  color: $subject-ink;
  font-family: inherit;
  font-size: 12px;
  line-height: 16px;
  font-weight: 700;
  cursor: pointer;
}
.st__btn--ghost {
  background: rgba($subject-cream, .18);
  color: $subject-ink;   // 주황 칩 면 위 크림 2.64:1 → 잉크 6.48:1
  box-shadow: inset 0 0 0 1px rgba($subject-cream, .55);
}
.st__btn:focus-visible { outline: 2px solid $subject-cream; outline-offset: 2px; }

// ── 사람이 만졌을 때의 진짜 동작 ──
@keyframes st-out {
  from { transform: translateX(0); opacity: 1; }
  to   { transform: translateX(-28px); opacity: 0; }
}
@keyframes st-in {
  from { transform: translateX(28px); opacity: 0; }
  to   { transform: translateX(0); opacity: 1; }
}
.st__item.is-out { animation: st-out $dur-base cubic-bezier(.2, .8, .2, 1) forwards; }
.st__item.is-in  { animation: st-in $dur-base cubic-bezier(.2, .8, .2, 1); }

// ── 격자 미리보기용 자동 루프 (2초) ──
// 뒤 두 칸이 시차를 두고 왼쪽으로 빠졌다가, 오른쪽에서 되돌아온다. 86% 에 끝난다
@keyframes st-slide {
  0%, 6%    { transform: translateX(0);     opacity: 1; }
  34%       { transform: translateX(-28px); opacity: 0; }
  46%       { transform: translateX(-28px); opacity: 0; }
  47%       { transform: translateX(28px);  opacity: 0; }
  58%       { transform: translateX(28px);  opacity: 0; }
  86%, 100% { transform: translateX(0);     opacity: 1; }
}
// animation 단축을 쓰면 delay 가 0 으로 리셋된다 — 낱개 속성으로 (240 실측)
.st.is-demo .st__item:nth-child(4),
.st.is-demo .st__item:nth-child(5) {
  animation-name: st-slide;
  animation-duration: $dur-loop;
  animation-timing-function: $ease-spring;
  animation-iteration-count: infinite;
}
.st.is-demo .st__item:nth-child(5) { animation-delay: 0s; }
.st.is-demo .st__item:nth-child(4) { animation-delay: .09s; }

@media (max-width: 340px) {
  .st { gap: $sp-2; }
  .st__rail { height: 40px; padding: 0 $sp-1; border-radius: $r-control; }
  .st__list { gap: 0; }
  .st__item { gap: 0; }
  .st__link { padding: 0 $sp-1; font-size: 11px; line-height: 16px; gap: 0; }
  .st__link svg { width: 11px; height: 11px; }
  .st__sep svg { width: 10px; height: 10px; }
  .st__btn { padding: $sp-1 $sp-2; font-size: 11px; line-height: 14px; }
}

@media (prefers-reduced-motion: reduce) {
  .st.is-demo .st__item { animation: none !important; }
  .st__item.is-out, .st__item.is-in { animation-duration: 1ms !important; }
  .st__link { transition: none; }
  .st__link:hover { transform: none; }
}

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);
}

.st {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  width: 100%;
  max-width: 392px;
}

.st__rail {
  box-sizing: border-box;
  width: 100%;
  height: 48px;
  overflow: hidden;
  display: flex;
  align-items: center;
  padding: 0 8px;
  border-radius: 16px;
  background: rgba(23, 20, 26, 0.92);
}

.st__nav {
  width: 100%;
}

.st__list {
  display: flex;
  align-items: center;
  flex-wrap: nowrap;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.st__item {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 0 0 auto;
}

.st__item[hidden] {
  display: none;
}

.st__sep {
  display: inline-flex;
  flex: none;
  color: rgba(255, 247, 230, 0.45);
}

.st__link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 8px;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.18);
  color: #fff7e6;
  font-size: 13px;
  line-height: 18px;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  transition: transform 300ms cubic-bezier(0.2, 0.8, 0.2, 1), background 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.st__link svg {
  flex: none;
}

.st__link:hover {
  background: rgba(255, 247, 230, 0.34);
  transform: translateY(-1px);
}

.st__link:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 2px;
}

.st__link--now {
  background: #fff7e6;
  color: #17141a;
  font-weight: 700;
  cursor: default;
}

.st__btns {
  display: flex;
  gap: 8px;
}

.st__btn {
  padding: 4px 12px;
  border: 0;
  border-radius: 999px;
  background: #fff7e6;
  color: #17141a;
  font-family: inherit;
  font-size: 12px;
  line-height: 16px;
  font-weight: 700;
  cursor: pointer;
}

.st__btn--ghost {
  background: rgba(255, 247, 230, 0.18);
  color: #17141a;
  box-shadow: inset 0 0 0 1px rgba(255, 247, 230, 0.55);
}

.st__btn:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 2px;
}

@keyframes st-out {
  from {
    transform: translateX(0);
    opacity: 1;
  }
  to {
    transform: translateX(-28px);
    opacity: 0;
  }
}
@keyframes st-in {
  from {
    transform: translateX(28px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}
.st__item.is-out {
  animation: st-out 300ms cubic-bezier(0.2, 0.8, 0.2, 1) forwards;
}

.st__item.is-in {
  animation: st-in 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

@keyframes st-slide {
  0%, 6% {
    transform: translateX(0);
    opacity: 1;
  }
  34% {
    transform: translateX(-28px);
    opacity: 0;
  }
  46% {
    transform: translateX(-28px);
    opacity: 0;
  }
  47% {
    transform: translateX(28px);
    opacity: 0;
  }
  58% {
    transform: translateX(28px);
    opacity: 0;
  }
  86%, 100% {
    transform: translateX(0);
    opacity: 1;
  }
}
.st.is-demo .st__item:nth-child(4),
.st.is-demo .st__item:nth-child(5) {
  animation-name: st-slide;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

.st.is-demo .st__item:nth-child(5) {
  animation-delay: 0s;
}

.st.is-demo .st__item:nth-child(4) {
  animation-delay: 0.09s;
}

@media (max-width: 340px) {
  .st {
    gap: 8px;
  }
  .st__rail {
    height: 40px;
    padding: 0 4px;
    border-radius: 12px;
  }
  .st__list {
    gap: 0;
  }
  .st__item {
    gap: 0;
  }
  .st__link {
    padding: 0 4px;
    font-size: 11px;
    line-height: 16px;
    gap: 0;
  }
  .st__link svg {
    width: 11px;
    height: 11px;
  }
  .st__sep svg {
    width: 10px;
    height: 10px;
  }
  .st__btn {
    padding: 4px 8px;
    font-size: 11px;
    line-height: 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .st.is-demo .st__item {
    animation: none !important;
  }
  .st__item.is-out, .st__item.is-in {
    animation-duration: 1ms !important;
  }
  .st__link {
    transition: none;
  }
  .st__link:hover {
    transform: none;
  }
}

// 실제 동작: 칸을 누르면 그 뒤 칸이 왼쪽으로 미끄러져 나가고(animationend 에서 hidden),
// 「下へ戻る」가 오른쪽에서 밀어 넣는다. 링크·버튼이라 Enter·Space 로도 같은 동작.
var root = document.getElementById('st');
var list = document.getElementById('st-list');
var items = [].slice.call(list.children);
function stop() { root.classList.remove('is-demo'); }
function leave(li) { li.classList.remove('is-in'); li.classList.add('is-out'); }
function enter(li) { li.hidden = false; li.classList.remove('is-out'); li.classList.add('is-in'); }
function lastVisible() {
  var k = -1;
  for (var i = 0; i < items.length; i++) { if (!items[i].hidden) k = i; }
  return k;
}
list.addEventListener('animationend', function (e) {
  var li = e.target.closest('.st__item');
  if (!li) return;
  if (li.classList.contains('is-out')) { li.hidden = true; li.classList.remove('is-out'); }
  else if (li.classList.contains('is-in')) { li.classList.remove('is-in'); }
});
list.addEventListener('click', function (e) {
  var a = e.target.closest('.st__link');
  if (!a || !a.hasAttribute('data-i')) return;
  e.preventDefault();
  stop();
  for (var k = items.length - 1; k > +a.getAttribute('data-i'); k--) {
    if (!items[k].hidden) leave(items[k]);
  }
});
document.getElementById('st-up').addEventListener('click', function () {
  stop();
  var k = lastVisible();
  if (k > 0) leave(items[k]);
});
document.getElementById('st-down').addEventListener('click', function () {
  stop();
  for (var k = 0; k < items.length; k++) { if (items[k].hidden) enter(items[k]); }
});

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

export type Crumb = { label: string; href?: string };

export type StepTransitionProps = {
  crumbs?: Crumb[];
  duration?: number;
  easing?: string;
  color?: string;
};

// 도구/demo.py 의 ambient.d.ts 는 React 이벤트 제네릭을 안 준다 — 로컬 타입으로 TS7006 을 막는다
type ClickEvt = { preventDefault(): void };
type AnimEvt = { currentTarget: { getAttribute(n: string): string | null } };
type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

const IconHouse = () => (
  <svg viewBox="0 0 256 256" width="14" height="14" aria-hidden="true"><g fill="currentColor"><path d="M216 120v96h-64v-64h-48v64H40v-96a8 8 0 0 1 2.34-5.66l80-80a8 8 0 0 1 11.32 0l80 80A8 8 0 0 1 216 120" opacity=".2"/><path d="m219.31 108.68l-80-80a16 16 0 0 0-22.62 0l-80 80A15.87 15.87 0 0 0 32 120v96a8 8 0 0 0 8 8h64a8 8 0 0 0 8-8v-56h32v56a8 8 0 0 0 8 8h64a8 8 0 0 0 8-8v-96a15.87 15.87 0 0 0-4.69-11.32M208 208h-48v-56a8 8 0 0 0-8-8h-48a8 8 0 0 0-8 8v56H48v-88l80-80l80 80Z"/></g></svg>
);
const IconCaretRight = () => (
  <svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m176 128l-80 80V48Z" opacity=".2"/><path d="m181.66 122.34l-80-80A8 8 0 0 0 88 48v160a8 8 0 0 0 13.66 5.66l80-80a8 8 0 0 0 0-11.32M104 188.69V67.31L164.69 128Z"/></g></svg>
);

const DEFAULT_CRUMBS: Crumb[] = [
  { label: "Home", href: "#" },
  { label: "Docs", href: "#" },
  { label: "2026", href: "#" },
  { label: "Sep", href: "#" },
  { label: "Invoice" },
];

export default function StepTransition({
  crumbs = DEFAULT_CRUMBS,
  duration = 300,
  easing = "cubic-bezier(.2, .8, .2, 1)",
  color = "#fff7e6",
}: StepTransitionProps) {
  const [shown, setShown] = useState(crumbs.length);   // 화면에 남은 칸 수
  const [leaving, setLeaving] = useState<number[]>([]); // 지금 왼쪽으로 빠지는 중인 칸
  const [entering, setEntering] = useState<number[]>([]);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  function cutTo(i: number) {
    const out: number[] = [];
    for (let k = shown - 1; k > i; k--) out.push(k);
    if (!out.length) return;
    setEntering([]);
    setLeaving(out);
  }

  function restore() {
    const back: number[] = [];
    for (let k = shown; k < crumbs.length; k++) back.push(k);
    if (!back.length) return;
    setLeaving([]);
    setShown(crumbs.length);
    setEntering(back);
  }

  function onEnd(e: AnimEvt) {
    const k = Number(e.currentTarget.getAttribute("data-k"));
    if (leaving.indexOf(k) >= 0) {
      setShown((p: number) => Math.min(p, k));
      setLeaving((p: number[]) => p.filter((x: number) => x !== k));
    } else {
      setEntering((p: number[]) => p.filter((x: number) => x !== k));
    }
  }

  return (
    <div className={styles.st} style={vars}>
      <div className={styles.rail}>
        <nav aria-label="Breadcrumb" className={styles.nav}>
          <ol className={styles.list}>
            {crumbs.map((c: Crumb, i: number) => {
              if (i >= shown && entering.indexOf(i) < 0) return null;
              const cls = [styles.item, leaving.indexOf(i) >= 0 ? styles.out : "", entering.indexOf(i) >= 0 ? styles.in : ""].join(" ");
              const last = i === crumbs.length - 1;
              return (
                <li key={c.label} className={cls} data-k={i} onAnimationEnd={onEnd}>
                  {i > 0 && <span className={styles.sep} aria-hidden="true"><IconCaretRight /></span>}
                  {last ? (
                    <span className={`${styles.link} ${styles.now}`} aria-current="page">{c.label}</span>
                  ) : (
                    <a className={styles.link} href={c.href} onClick={(e: ClickEvt): void => { e.preventDefault(); cutTo(i); }}>
                      {i === 0 && <IconHouse />}{c.label}
                    </a>
                  )}
                </li>
              );
            })}
          </ol>
        </nav>
      </div>
      <div className={styles.btns}>
        <button type="button" className={styles.btn} onClick={(): void => cutTo(shown - 2)}>Go up</button>
        <button type="button" className={`${styles.btn} ${styles.ghost}`} onClick={restore}>Go back down</button>
      </div>
    </div>
  );
}