04Sibling path preview

<main class="stage">
  <nav class="sp is-demo" aria-label="Breadcrumb">
    <ol class="sp__list">
      <li class="sp__item">
        <a class="sp__crumb" href="#">Home</a>
        <span class="sp__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>
      </li>
      <li class="sp__item sp__item--menu" id="sp-item">
        <button class="sp__crumb sp__crumb--btn" type="button" id="sp-btn" aria-haspopup="menu" aria-expanded="false" aria-controls="sp-menu">
          <span class="sp__txt" id="sp-txt">Electronics</span>
          <svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m208 96l-80 80l-80-80Z" opacity=".2"/><path d="M215.39 92.94A8 8 0 0 0 208 88H48a8 8 0 0 0-5.66 13.66l80 80a8 8 0 0 0 11.32 0l80-80a8 8 0 0 0 1.73-8.72M128 164.69L67.31 104h121.38Z"/></g></svg>
        </button>
        <ul class="sp__menu" role="menu" id="sp-menu" aria-label="Categories beside Electronics">
          <li class="sp__opt" role="none"><a class="sp__mlink" role="menuitem" tabindex="-1" href="#">Appliances</a></li>
          <li class="sp__opt" role="none"><a class="sp__mlink" role="menuitem" tabindex="-1" href="#">Audio</a></li>
          <li class="sp__opt" role="none"><a class="sp__mlink" role="menuitem" tabindex="-1" href="#">Cameras</a></li>
        </ul>
        <span class="sp__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>
      </li>
      <li class="sp__item">
        <a class="sp__crumb" href="#">Laptops</a>
        <span class="sp__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>
      </li>
      <li class="sp__item">
        <span class="sp__crumb sp__crumb--now" aria-current="page">13-inch gaming</span>
      </li>
    </ol>
    <span class="sp__cursor" aria-hidden="true"></span>
  </nav>
</main>

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

$duration: $dur-quick;
$easing: $ease-spring;
$color: $subject-blue;

@include stage($stage-paper);

// 뿌리 — 절대배치 목록은 부모 높이에서 빠지지만 scrollHeight 엔 잡힌다.
// 그래서 열린 목록 높이(86px)만큼 padding-bottom 으로 미리 자리를 잡아 둔다 (BD9)
.sp {
  position: relative;
  padding-bottom: 88px;
  color: $subject-ink;
  font-size: clamp(11px, 3vw, 13px);
  line-height: 18px;
  user-select: none;
  -webkit-user-select: none;
}

.sp__list {
  display: flex;
  align-items: center;
  flex-wrap: nowrap;
  margin: 0;
  padding: 0;
  list-style: none;
}
.sp__item {
  display: flex;
  align-items: center;
  white-space: nowrap;
}
.sp__item--menu { position: relative; }

.sp__sep {
  display: inline-flex;
  margin: 0 $sp-1;
  color: rgba($subject-ink, .38);
}
.sp__sep svg { display: block; }

.sp__crumb {
  display: inline-flex;
  align-items: center;
  gap: $sp-1;
  padding: $sp-1 $sp-2;
  border: 0;
  border-radius: $r-sm;
  background: transparent;
  color: rgba($subject-ink, .72);
  font-family: inherit;
  font-size: inherit;
  line-height: 18px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: background $duration $easing, color $duration $easing;
}
.sp__crumb:hover { background: rgba($subject-blue, .12); color: $color; }
.sp__crumb:focus-visible { outline: 2px solid $color; outline-offset: 2px; }
.sp__crumb--btn { cursor: pointer; }
.sp__crumb--now {
  color: $subject-ink;
  font-weight: 800;
  cursor: default;
}
.sp__crumb--now:hover { background: transparent; color: $subject-ink; }

.sp__crumb--btn svg {
  display: block;
  transition: transform $duration $easing;
}
.sp__item--menu.is-open .sp__crumb--btn { background: rgba($subject-blue, .12); color: $color; }
.sp__item--menu.is-open .sp__crumb--btn svg { transform: rotate(180deg); }

// 형제 목록 — 아래로 펼친다. 항목 높이 24px × 3 + 패딩 8 + 테두리 2 = 82px
.sp__menu {
  position: absolute;
  top: calc(100% + #{$sp-1});
  left: 0;
  z-index: 2;
  min-width: 112px;
  margin: 0;
  padding: $sp-1;
  list-style: none;
  border: 1px solid rgba($subject-ink, .14);
  border-radius: $r-control;
  background: $subject-cream;
  box-shadow: $shadow-press;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity $duration $easing, transform $duration $easing, visibility $duration $easing;
}
.sp__item--menu.is-open .sp__menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.sp__opt { display: block; }
.sp__mlink {
  display: flex;
  align-items: center;
  height: 24px;
  padding: 0 $sp-2;
  border-radius: $r-xs;
  color: rgba($subject-ink, .78);
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}
.sp__mlink:hover,
.sp__mlink:focus-visible {
  outline: none;
  background: $color;
  color: $subject-cream;
}

// 커서 점 — 자동 루프에서만 보인다
.sp__cursor {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 3;
  width: 12px;
  height: 12px;
  border: 2px solid $subject-cream;
  border-radius: 50%;
  background: $subject-ink;
  box-shadow: $shadow-press;
  opacity: 0;
  pointer-events: none;
  transform: translate(4px, 92px);
}

// ── 자동 루프(2초): 커서가 칸으로 이동 → 목록 펼침 → 두 번째 항목으로 → 닫히고 복귀(86%) ──
.sp.is-demo .sp__cursor {
  opacity: 1;
  animation-name: sp-cursor;
  animation-duration: $dur-loop;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
@keyframes sp-cursor {
  0%, 2%    { transform: translate(4px, 92px); }
  26%, 40%  { transform: translate(110px, 20px); }
  72%       { transform: translate(112px, 58px); }
  86%, 100% { transform: translate(4px, 92px); }
}

.sp.is-demo .sp__menu {
  visibility: visible;
  pointer-events: none;
  transition: none;
  animation-name: sp-open;
  animation-duration: $dur-loop;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
@keyframes sp-open {
  0%, 26%   { opacity: 0; transform: translateY(-6px); }
  40%, 72%  { opacity: 1; transform: translateY(0); }
  86%, 100% { opacity: 0; transform: translateY(-6px); }
}

.sp.is-demo .sp__crumb--btn {
  animation-name: sp-btn;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
@keyframes sp-btn {
  0%, 24%   { background-color: rgba($subject-blue, 0); }
  26%, 84%  { background-color: rgba($subject-blue, .14); }
  86%, 100% { background-color: rgba($subject-blue, 0); }
}

// 두 번째 항목 강조 — 크로스페이드 금지, 한 프레임에 컷
.sp.is-demo .sp__opt:nth-child(2) .sp__mlink {
  animation-name: sp-pick;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
@keyframes sp-pick {
  0%, 60%   { background-color: rgba($subject-blue, 0); color: rgba($subject-ink, .78); }
  62%, 78%  { background-color: rgba($subject-blue, 1); color: $subject-cream; }
  80%, 100% { background-color: rgba($subject-blue, 0); color: rgba($subject-ink, .78); }
}

@media (prefers-reduced-motion: reduce) {
  .sp.is-demo .sp__cursor,
  .sp.is-demo .sp__menu,
  .sp.is-demo .sp__crumb--btn,
  .sp.is-demo .sp__opt:nth-child(2) .sp__mlink { animation: none !important; }
  .sp__menu, .sp__crumb, .sp__crumb--btn svg { transition: none; }
  .sp.is-demo .sp__menu { opacity: 1; transform: translateY(0); }
}

@media (max-width: 340px) {
  .sp { padding-bottom: 84px; }
  .sp__crumb { padding: $sp-1; }
  .sp__sep { margin: 0; }
  .sp__menu { min-width: 96px; }
}

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 {
  position: relative;
  padding-bottom: 88px;
  color: #17141a;
  font-size: clamp(11px, 3vw, 13px);
  line-height: 18px;
  user-select: none;
  -webkit-user-select: none;
}

.sp__list {
  display: flex;
  align-items: center;
  flex-wrap: nowrap;
  margin: 0;
  padding: 0;
  list-style: none;
}

.sp__item {
  display: flex;
  align-items: center;
  white-space: nowrap;
}

.sp__item--menu {
  position: relative;
}

.sp__sep {
  display: inline-flex;
  margin: 0 4px;
  color: rgba(23, 20, 26, 0.38);
}

.sp__sep svg {
  display: block;
}

.sp__crumb {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 8px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: rgba(23, 20, 26, 0.72);
  font-family: inherit;
  font-size: inherit;
  line-height: 18px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: background 220ms cubic-bezier(0.2, 0.8, 0.2, 1), color 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.sp__crumb:hover {
  background: rgba(47, 109, 246, 0.12);
  color: #2f6df6;
}

.sp__crumb:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}

.sp__crumb--btn {
  cursor: pointer;
}

.sp__crumb--now {
  color: #17141a;
  font-weight: 800;
  cursor: default;
}

.sp__crumb--now:hover {
  background: transparent;
  color: #17141a;
}

.sp__crumb--btn svg {
  display: block;
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.sp__item--menu.is-open .sp__crumb--btn {
  background: rgba(47, 109, 246, 0.12);
  color: #2f6df6;
}

.sp__item--menu.is-open .sp__crumb--btn svg {
  transform: rotate(180deg);
}

.sp__menu {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  z-index: 2;
  min-width: 112px;
  margin: 0;
  padding: 4px;
  list-style: none;
  border: 1px solid rgba(23, 20, 26, 0.14);
  border-radius: 12px;
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity 220ms cubic-bezier(0.2, 0.8, 0.2, 1), transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1), visibility 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.sp__item--menu.is-open .sp__menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.sp__opt {
  display: block;
}

.sp__mlink {
  display: flex;
  align-items: center;
  height: 24px;
  padding: 0 8px;
  border-radius: 4px;
  color: rgba(23, 20, 26, 0.78);
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}

.sp__mlink:hover,
.sp__mlink:focus-visible {
  outline: none;
  background: #2f6df6;
  color: #fff7e6;
}

.sp__cursor {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 3;
  width: 12px;
  height: 12px;
  border: 2px solid #fff7e6;
  border-radius: 50%;
  background: #17141a;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  opacity: 0;
  pointer-events: none;
  transform: translate(4px, 92px);
}

.sp.is-demo .sp__cursor {
  opacity: 1;
  animation-name: sp-cursor;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

@keyframes sp-cursor {
  0%, 2% {
    transform: translate(4px, 92px);
  }
  26%, 40% {
    transform: translate(110px, 20px);
  }
  72% {
    transform: translate(112px, 58px);
  }
  86%, 100% {
    transform: translate(4px, 92px);
  }
}
.sp.is-demo .sp__menu {
  visibility: visible;
  pointer-events: none;
  transition: none;
  animation-name: sp-open;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

@keyframes sp-open {
  0%, 26% {
    opacity: 0;
    transform: translateY(-6px);
  }
  40%, 72% {
    opacity: 1;
    transform: translateY(0);
  }
  86%, 100% {
    opacity: 0;
    transform: translateY(-6px);
  }
}
.sp.is-demo .sp__crumb--btn {
  animation-name: sp-btn;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes sp-btn {
  0%, 24% {
    background-color: rgba(47, 109, 246, 0);
  }
  26%, 84% {
    background-color: rgba(47, 109, 246, 0.14);
  }
  86%, 100% {
    background-color: rgba(47, 109, 246, 0);
  }
}
.sp.is-demo .sp__opt:nth-child(2) .sp__mlink {
  animation-name: sp-pick;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes sp-pick {
  0%, 60% {
    background-color: rgba(47, 109, 246, 0);
    color: rgba(23, 20, 26, 0.78);
  }
  62%, 78% {
    background-color: #2f6df6;
    color: #fff7e6;
  }
  80%, 100% {
    background-color: rgba(47, 109, 246, 0);
    color: rgba(23, 20, 26, 0.78);
  }
}
@media (prefers-reduced-motion: reduce) {
  .sp.is-demo .sp__cursor,
  .sp.is-demo .sp__menu,
  .sp.is-demo .sp__crumb--btn,
  .sp.is-demo .sp__opt:nth-child(2) .sp__mlink {
    animation: none !important;
  }
  .sp__menu, .sp__crumb, .sp__crumb--btn svg {
    transition: none;
  }
  .sp.is-demo .sp__menu {
    opacity: 1;
    transform: translateY(0);
  }
}
@media (max-width: 340px) {
  .sp {
    padding-bottom: 84px;
  }
  .sp__crumb {
    padding: 4px;
  }
  .sp__sep {
    margin: 0;
  }
  .sp__menu {
    min-width: 96px;
  }
}

// 실동작: 마우스로 열고 닫기 · ArrowDown 으로 열어 첫 항목 포커스 · 목록 안 위아래 이동 · Escape 로 닫고 복귀
var root = document.querySelector('.sp');
var item = document.getElementById('sp-item');
var btn = document.getElementById('sp-btn');
var txt = document.getElementById('sp-txt');
var menu = document.getElementById('sp-menu');
var opts = [].slice.call(menu.querySelectorAll('[role="menuitem"]'));
function live() { root.classList.remove('is-demo'); }
function open(first) {
  live();
  item.classList.add('is-open');
  btn.setAttribute('aria-expanded', 'true');
  if (first) opts[0].focus({ preventScroll: true });
}
function shut(back) {
  item.classList.remove('is-open');
  btn.setAttribute('aria-expanded', 'false');
  if (back) btn.focus({ preventScroll: true });
}
item.addEventListener('pointerenter', function () { open(false); });
item.addEventListener('pointerleave', function () { shut(false); });
btn.addEventListener('click', function (e) {
  e.preventDefault();
  if (item.classList.contains('is-open')) shut(false); else open(true);
});
btn.addEventListener('keydown', function (e) {
  if (e.key === 'ArrowDown') { e.preventDefault(); open(true); }
  else if (e.key === 'Escape') { shut(false); }
});
menu.addEventListener('keydown', function (e) {
  var i = opts.indexOf(document.activeElement);
  if (e.key === 'ArrowDown') { e.preventDefault(); live(); opts[(i + 1) % opts.length].focus({ preventScroll: true }); }
  else if (e.key === 'ArrowUp') { e.preventDefault(); live(); opts[(i - 1 + opts.length) % opts.length].focus({ preventScroll: true }); }
  else if (e.key === 'Escape') { e.preventDefault(); shut(true); }
});
opts.forEach(function (o) {
  o.addEventListener('click', function (e) { e.preventDefault(); txt.textContent = o.textContent; shut(true); });
});

import { useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./SiblingPreview.module.scss";

export type SiblingPreviewProps = {
  siblings?: string[];
  duration?: number;
  easing?: string;
  color?: string;
};

type KeyEvt = { key: string; preventDefault(): void };
type ClickEvt = { preventDefault(): void };
type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

const CaretRight = () => (
  <span className={styles.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>
);
const CaretDown = () => (
  <svg viewBox="0 0 256 256" width="12" height="12" aria-hidden="true"><g fill="currentColor"><path d="m208 96l-80 80l-80-80Z" opacity=".2"/><path d="M215.39 92.94A8 8 0 0 0 208 88H48a8 8 0 0 0-5.66 13.66l80 80a8 8 0 0 0 11.32 0l80-80a8 8 0 0 0 1.73-8.72M128 164.69L67.31 104h121.38Z"/></g></svg>
);

export default function SiblingPreview({
  siblings = ["Appliances", "Audio", "Cameras"],
  duration = 220,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: SiblingPreviewProps) {
  const [open, setOpen] = useState(false);
  const [label, setLabel] = useState("Electronics");
  const btnRef = useRef<HTMLButtonElement>(null);
  const menuRef = useRef<HTMLUListElement>(null);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  function links(): HTMLElement[] {
    const m = menuRef.current;
    if (!m) return [];
    return Array.prototype.slice.call(m.querySelectorAll('[role="menuitem"]')) as HTMLElement[];
  }
  function focusAt(i: number): void {
    const l = links();
    if (!l.length) return;
    l[((i % l.length) + l.length) % l.length].focus({ preventScroll: true });
  }
  function onBtnKey(e: KeyEvt): void {
    if (e.key === "ArrowDown") {
      e.preventDefault();
      setOpen(true);
      window.setTimeout(() => focusAt(0), 0);
    } else if (e.key === "Escape") {
      setOpen(false);
    }
  }
  function onMenuKey(e: KeyEvt): void {
    const l = links();
    const i = l.indexOf(document.activeElement as HTMLElement);
    if (e.key === "ArrowDown") { e.preventDefault(); focusAt(i + 1); }
    else if (e.key === "ArrowUp") { e.preventDefault(); focusAt(i - 1); }
    else if (e.key === "Escape") {
      e.preventDefault();
      setOpen(false);
      if (btnRef.current) btnRef.current.focus({ preventScroll: true });
    }
  }
  function pick(e: ClickEvt, name: string): void {
    e.preventDefault();
    setLabel(name);
    setOpen(false);
    if (btnRef.current) btnRef.current.focus({ preventScroll: true });
  }

  return (
    <nav className={styles.sp} style={vars} aria-label="Breadcrumb">
      <ol className={styles.list}>
        <li className={styles.item}>
          <a className={styles.crumb} href="#">Home</a>
          <CaretRight />
        </li>
        <li
          className={open ? `${styles.item} ${styles.hasMenu} ${styles.isOpen}` : `${styles.item} ${styles.hasMenu}`}
          onPointerEnter={(): void => setOpen(true)}
          onPointerLeave={(): void => setOpen(false)}
        >
          <button
            ref={btnRef}
            type="button"
            className={`${styles.crumb} ${styles.crumbBtn}`}
            aria-haspopup="menu"
            aria-expanded={open}
            onKeyDown={onBtnKey}
            onClick={(): void => setOpen(!open)}
          >
            <span>{label}</span>
            <CaretDown />
          </button>
          <ul
            ref={menuRef}
            className={styles.menu}
            role="menu"
            aria-label="Categories beside Electronics"
            onKeyDown={onMenuKey}
          >
            {siblings.map((s: string) => (
              <li className={styles.opt} role="none" key={s}>
                <a className={styles.mlink} role="menuitem" tabIndex={-1} href="#" onClick={(e: ClickEvt): void => pick(e, s)}>{s}</a>
              </li>
            ))}
          </ul>
          <CaretRight />
        </li>
        <li className={styles.item}>
          <a className={styles.crumb} href="#">Laptops</a>
          <CaretRight />
        </li>
        <li className={styles.item}>
          <span className={`${styles.crumb} ${styles.now}`} aria-current="page">13-inch gaming</span>
        </li>
      </ol>
    </nav>
  );
}