04Mở bằng clip-path

<main class="stage">
  <div class="card">
    <span class="card__title">Tiêu đề tài liệu</span>
    <nav class="menu is-demo">
      <button class="menu__trigger" type="button" aria-expanded="false" aria-label="Xem thêm">⋯</button>
      <ul class="menu__panel">
        <li><a href="#">Sửa</a></li>
        <li><a href="#">Nhân bản</a></li>
        <li><a href="#">Xóa</a></li>
      </ul>
    </nav>
  </div>
</main>

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

$duration: $dur-base;                              // 클립이 펼쳐지는 시간
$easing: $ease-out;                                // 시작 빠르고 끝은 부드럽게
$color: $subject-blue;                             // 문서 카드 강조 색

@include stage($stage-paper);

.card {
  position: relative;
  align-self: flex-start;                            // 패널이 트리거 아래로 열려 무대 중앙에 두면 320px 에서 아래로 넘친다 — 위로 붙여 여유를 둔다 (실측 320px 재검증 2026-09-10)
  width: min(240px, 88vw);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  border-radius: $r-card;
  background: $subject-cream;
  box-shadow: $shadow-press;
  font-weight: 600;
  font-size: clamp(13px, 3.6vw, 16px);
  line-height: 1.2;
  font-family: inherit;
  color: $stage-ink;
  border-left: 4px solid $color;
}

.menu {
  position: relative;
  font-weight: 500;
  font-size: clamp(13px, 3.6vw, 16px);
  line-height: 1.4;
  font-family: inherit;

  &__trigger {
    border: 0;
    border-radius: $r-control;
    width: 32px;
    height: 32px;
    font-weight: 700;
    font-size: 18px;
    line-height: 1;
    font-family: inherit;
    color: $stage-ink;
    background: transparent;
    cursor: pointer;
  }
  &__trigger:hover { background: rgba($stage-ink, .06); }

  &__panel {
    position: absolute;
    top: calc(100% + 4px);
    right: 0;
    width: max-content;
    max-width: min(140px, 70vw);
    margin: 0;
    padding: 6px;
    list-style: none;
    background: #fff;
    border-radius: $r-control;
    box-shadow: $shadow-raised;
    clip-path: inset(0 0 100% 0);                    // 위에서부터 잘려 보이지 않던 것이 펼쳐진다
    pointer-events: none;
  }

  &__panel li a {
    display: block;
    padding: 8px 10px;
    border-radius: $r-control - 4px;
    color: $stage-ink;
    text-decoration: none;
  }
  &__panel li a:hover { background: rgba($stage-ink, .06); }

  &.is-open &__panel { clip-path: inset(0 0 0% 0); pointer-events: auto; transition: clip-path $duration $easing; }
  &.is-demo &__panel { animation: reveal-loop $dur-loop $easing infinite; }
}

@keyframes reveal-loop {
  0%, 30%   { clip-path: inset(0 0 100% 0); }
  45%, 80%  { clip-path: inset(0 0 0% 0); }
  95%, 100% { clip-path: inset(0 0 100% 0); }
}

@media (prefers-reduced-motion: reduce) {
  .menu__panel { transition: none !important; }
  .menu.is-demo .menu__panel { animation: none; clip-path: inset(0 0 100% 0); }
}

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);
}

.card {
  position: relative;
  align-self: flex-start;
  width: min(240px, 88vw);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  border-radius: 16px;
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  font-weight: 600;
  font-size: clamp(13px, 3.6vw, 16px);
  line-height: 1.2;
  font-family: inherit;
  color: #17141a;
  border-left: 4px solid #2f6df6;
}

.menu {
  position: relative;
  font-weight: 500;
  font-size: clamp(13px, 3.6vw, 16px);
  line-height: 1.4;
  font-family: inherit;
}
.menu__trigger {
  border: 0;
  border-radius: 12px;
  width: 32px;
  height: 32px;
  font-weight: 700;
  font-size: 18px;
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  background: transparent;
  cursor: pointer;
}
.menu__trigger:hover {
  background: rgba(23, 20, 26, 0.06);
}
.menu__panel {
  position: absolute;
  top: calc(100% + 4px);
  right: 0;
  width: max-content;
  max-width: min(140px, 70vw);
  margin: 0;
  padding: 6px;
  list-style: none;
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  clip-path: inset(0 0 100% 0);
  pointer-events: none;
}
.menu__panel li a {
  display: block;
  padding: 8px 10px;
  border-radius: 8px;
  color: #17141a;
  text-decoration: none;
}
.menu__panel li a:hover {
  background: rgba(23, 20, 26, 0.06);
}
.menu.is-open .menu__panel {
  clip-path: inset(0 0 0% 0);
  pointer-events: auto;
  transition: clip-path 300ms ease-out;
}
.menu.is-demo .menu__panel {
  animation: reveal-loop 2s ease-out infinite;
}

@keyframes reveal-loop {
  0%, 30% {
    clip-path: inset(0 0 100% 0);
  }
  45%, 80% {
    clip-path: inset(0 0 0% 0);
  }
  95%, 100% {
    clip-path: inset(0 0 100% 0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .menu__panel {
    transition: none !important;
  }
  .menu.is-demo .menu__panel {
    animation: none;
    clip-path: inset(0 0 100% 0);
  }
}

// 트리거를 클릭하면 열리고 닫힌다. 데모(.is-demo)는 스스로 반복한다.
var m = document.querySelector('.menu'), t = m.querySelector('.menu__trigger');
t.addEventListener('click', function () {
  m.classList.remove('is-demo');
  t.setAttribute('aria-expanded', m.classList.toggle('is-open'));
});

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

export type ClipOpenDropdownProps = {
  title: string;
  moreLabel: string;
  items: string[];
  /** 클립이 펼쳐지는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function ClipOpenDropdown({
  title,
  moreLabel,
  items,
  duration = 300,
  easing = "ease-out",
  color = "#2f6df6",
}: ClipOpenDropdownProps) {
  const [open, setOpen] = useState(false);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.card} style={vars}>
      <span className={styles.title}>{title}</span>
      <nav className={styles.menu}>
        <button type="button" className={styles.trigger} aria-expanded={open} aria-label={moreLabel} onClick={() => setOpen((v) => !v)}>
          ⋯
        </button>
        <ul className={open ? `${styles.panel} ${styles.panelOpen}` : styles.panel}>
          {items.map((label) => (
            <li key={label}><a href="#">{label}</a></li>
          ))}
        </ul>
      </nav>
    </div>
  );
}