05Tự động phát chỉ bằng CSS

<main class="stage">
  <div class="ap">
    <div class="ap__track">
      <div class="ap__slide ap__slide--1"><span class="ap__cap">Đang diễn ra</span></div>
      <div class="ap__slide ap__slide--2"><span class="ap__cap">Ưu đãi thành viên mới</span></div>
      <div class="ap__slide ap__slide--3"><span class="ap__cap">Giảm giá mùa đông</span></div>
      <div class="ap__slide ap__slide--4"><span class="ap__cap">Coupon thành viên</span></div>
      <div class="ap__slide ap__slide--1" aria-hidden="true"><span class="ap__cap">Đang diễn ra</span></div>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;                 // 한 바퀴(슬라이드 4장) 도는 총 시간
$easing: $ease-out;
$color: $subject-blue;

@include stage($stage-ink);

.ap { width: min(400px, 92vw); overflow: hidden; border-radius: $r-card; }

// ── 실제 동작: 트랙 하나가 @keyframes 로 무한 반복 — 0줄 JS, 클릭할 것도 없다 ──
// 무한 루프 이음새: 1번을 트랙 끝에 복제(aria-hidden)해 그 복제본까지 정상 속도로 가고
// 100%→0% 재시작 점프는 복제본이 1번과 같아 안 보인다 (끝→처음 텔레포트 금지, 사용자 2026-09-11)
.ap__track {
  display: flex;
  width: 500%;
  animation: ap-cycle $duration $easing infinite;
}
// 마우스를 올리면 잠깐 멈춰 원하는 사진을 볼 수 있다 (호버 == 진짜 사용자 조작, 여전히 0줄 JS)
.ap:hover .ap__track { animation-play-state: paused; }

.ap__slide {
  flex: 0 0 20%;
  aspect-ratio: 16 / 9;
  margin-right: $sp-3;
  border-radius: $r-card;
  position: relative;
  overflow: hidden;
  display: grid;
  place-items: end start;
  box-sizing: border-box;
}
.ap__slide:last-child { margin-right: 0; }
.ap__slide::before {
  content: ""; position: absolute; top: $sp-4; right: $sp-4;
  width: $sp-10; height: $sp-10; border-radius: 50%;
  background: rgba(255, 255, 255, .85);
}
.ap__slide::after {
  content: ""; position: absolute; left: -8%; right: -8%; bottom: -6%; height: 52%;
  background: rgba(23, 20, 26, .28);
  clip-path: polygon(0% 100%, 20% 38%, 40% 64%, 58% 24%, 76% 58%, 100% 32%, 100% 100%);
}
.ap__slide--1 { background: linear-gradient(135deg, $color, #d6ddeb); }
.ap__slide--2 { background: linear-gradient(135deg, $stage-orange, #ebdbd6); }
.ap__slide--3 { background: linear-gradient(135deg, #c2ae82, $stage-yellow); }
.ap__slide--4 { background: linear-gradient(135deg, $subject-ink, #4a3f5c); }
.ap__cap {
  position: relative; z-index: 1;
  margin: $sp-4;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(23, 20, 26, .38);
  color: $subject-cream;
  font-weight: 600;
  font-size: clamp(12px, 3.2vw, 14px);
  line-height: 1;
  font-family: inherit;
}

// 한 칸 = 트랙(500%)의 -20% + 슬라이드 간 $sp-3 간격. 마지막(5번째) 칸은 1번의 복제본
@keyframes ap-cycle {
  0%, 8%    { transform: translateX(0%); }
  23%, 31%  { transform: translateX(calc(-20% - #{$sp-3})); }
  46%, 54%  { transform: translateX(calc(-40% - #{$sp-3 * 2})); }
  69%, 77%  { transform: translateX(calc(-60% - #{$sp-3 * 3})); }
  92%, 100% { transform: translateX(calc(-80% - #{$sp-3 * 4})); }
}

// ── 접근성 ──────────────────────────────────────────
@media (prefers-reduced-motion: reduce) {
  .ap__track { animation: none !important; transform: translateX(0%); }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ap {
  width: min(400px, 92vw);
  overflow: hidden;
  border-radius: 16px;
}

.ap__track {
  display: flex;
  width: 500%;
  animation: ap-cycle 2s ease-out infinite;
}

.ap:hover .ap__track {
  animation-play-state: paused;
}

.ap__slide {
  flex: 0 0 20%;
  aspect-ratio: 16/9;
  margin-right: 12px;
  border-radius: 16px;
  position: relative;
  overflow: hidden;
  display: grid;
  place-items: end start;
  box-sizing: border-box;
}

.ap__slide:last-child {
  margin-right: 0;
}

.ap__slide::before {
  content: "";
  position: absolute;
  top: 16px;
  right: 16px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.85);
}

.ap__slide::after {
  content: "";
  position: absolute;
  left: -8%;
  right: -8%;
  bottom: -6%;
  height: 52%;
  background: rgba(23, 20, 26, 0.28);
  clip-path: polygon(0% 100%, 20% 38%, 40% 64%, 58% 24%, 76% 58%, 100% 32%, 100% 100%);
}

.ap__slide--1 {
  background: linear-gradient(135deg, #2f6df6, #d6ddeb);
}

.ap__slide--2 {
  background: linear-gradient(135deg, #ff4d1f, #ebdbd6);
}

.ap__slide--3 {
  background: linear-gradient(135deg, #c2ae82, #ffd23f);
}

.ap__slide--4 {
  background: linear-gradient(135deg, #17141a, #4a3f5c);
}

.ap__cap {
  position: relative;
  z-index: 1;
  margin: 16px;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.38);
  color: #fff7e6;
  font-weight: 600;
  font-size: clamp(12px, 3.2vw, 14px);
  line-height: 1;
  font-family: inherit;
}

@keyframes ap-cycle {
  0%, 8% {
    transform: translateX(0%);
  }
  23%, 31% {
    transform: translateX(calc(-20% - 12px));
  }
  46%, 54% {
    transform: translateX(calc(-40% - 24px));
  }
  69%, 77% {
    transform: translateX(calc(-60% - 36px));
  }
  92%, 100% {
    transform: translateX(calc(-80% - 48px));
  }
}
@media (prefers-reduced-motion: reduce) {
  .ap__track {
    animation: none !important;
    transform: translateX(0%);
  }
}

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

const SLIDES = ["지금 진행 중", "신규 가입 혜택", "겨울 시즌 오프", "회원 전용 쿠폰"];

export type AutoplayCssProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function AutoplayCss({ duration = 2000, easing = "ease-out", color = "#2f6df6" }: AutoplayCssProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={styles.ap} style={vars}>
      {/* 아무것도 누르지 않아도 트랙 하나가 @keyframes 로 무한 반복 — 0줄 JS */}
      {/* 끝에는 첫 장의 복제본이 한 장 더 — 마지막→처음 되돌아감이 순간이동으로 보이지 않는다 (텔레포트 금지) */}
      <div className={styles.track}>
        {SLIDES.map((label, i) => (
          <div key={label} className={`${styles.slide} ${styles["slide" + (i + 1)]}`}>
            <span className={styles.cap}>{label}</span>
          </div>
        ))}
        <div className={`${styles.slide} ${styles.slide1}`} aria-hidden="true">
          <span className={styles.cap}>{SLIDES[0]}</span>
        </div>
      </div>
    </div>
  );
}