02Radio + arrow slider

<main class="stage">
  <div class="ra is-demo">
    <input type="radio" name="ra-tab" id="ra-1" class="ra__radio" checked>
    <input type="radio" name="ra-tab" id="ra-2" class="ra__radio">
    <input type="radio" name="ra-tab" id="ra-3" class="ra__radio">
    <div class="ra__viewport">
      <div class="ra__track">
        <div class="ra__slide ra__slide--1">
          <label class="ra__next" for="ra-2" aria-label="Next slide">›</label>
        </div>
        <div class="ra__slide ra__slide--2">
          <label class="ra__prev" for="ra-1" aria-label="Previous slide">‹</label>
          <label class="ra__next" for="ra-3" aria-label="Next slide">›</label>
        </div>
        <div class="ra__slide ra__slide--3">
          <label class="ra__prev" for="ra-2" aria-label="Previous slide">‹</label>
        </div>
        <div class="ra__slide ra__slide--1" aria-hidden="true">
          <span class="ra__next" aria-hidden="true">›</span>
        </div>
      </div>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;
$easing: $ease-spring;
$color: $stage-orange;

@include stage($stage-yellow);

.ra { width: min(360px, 88vw); }
.ra__radio { position: absolute; opacity: 0; pointer-events: none; }

// ── 실제 동작: 고른 라디오에 맞춰 트랙 전체가 밀린다 (형제결합자 + :checked, 0줄 JS) ──
// 트랙 끝에는 1번의 복제본(aria-hidden)이 한 장 더 — 예고편 루프의 끝→처음 점프를 숨긴다 (텔레포트 금지)
.ra__viewport { overflow: hidden; border-radius: $r-card; }
.ra__track {
  display: flex;
  width: 400%;
  transition: transform $duration $easing;
}
#ra-1:checked ~ .ra__viewport .ra__track { transform: translateX(0%); }
#ra-2:checked ~ .ra__viewport .ra__track { transform: translateX(-25%); }
#ra-3:checked ~ .ra__viewport .ra__track { transform: translateX(-50%); }

.ra__slide {
  flex: 0 0 25%;
  aspect-ratio: 16 / 9;
  position: relative;
  display: grid;
}
.ra__slide--1 { background: linear-gradient(135deg, $subject-ink, #4a3f5c); }
.ra__slide--2 { background: linear-gradient(135deg, $color, #ebdbd6); }
.ra__slide--3 { background: linear-gradient(135deg, $subject-blue, #d6ddeb); }

.ra__prev, .ra__next {
  position: absolute; top: 50%; transform: translateY(-50%);
  width: $sp-8; height: $sp-8;
  display: grid; place-items: center;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .85);
  color: $subject-ink;
  font-weight: 700;
  font-size: 20px;
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  box-shadow: $shadow-press;
}
.ra__prev { left: $sp-3; }
.ra__next { right: $sp-3; }

// ── 데모 루프: 클릭 전까지 라디오가 스스로 1→2→3→1 순으로 넘어간다 (checked 는 1번 그대로) ──
// 마지막 칸(-75%)은 1번의 복제본 — 100%→0% 점프가 복제본=1번이라 안 보인다
.ra.is-demo .ra__viewport .ra__track { animation: ra-loop $dur-loop $easing infinite; }
@keyframes ra-loop {
  0%, 8%    { transform: translateX(0%); }
  31%, 39%  { transform: translateX(-25%); }
  62%, 70%  { transform: translateX(-50%); }
  92%, 100% { transform: translateX(-75%); }
}

// ── 접근성 ──────────────────────────────────────────
@media (prefers-reduced-motion: reduce) {
  .ra__track { transition: none; }
  .ra.is-demo .ra__viewport .ra__track { animation: none !important; }
}

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);
}

.ra {
  width: min(360px, 88vw);
}

.ra__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.ra__viewport {
  overflow: hidden;
  border-radius: 16px;
}

.ra__track {
  display: flex;
  width: 400%;
  transition: transform 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

#ra-1:checked ~ .ra__viewport .ra__track {
  transform: translateX(0%);
}

#ra-2:checked ~ .ra__viewport .ra__track {
  transform: translateX(-25%);
}

#ra-3:checked ~ .ra__viewport .ra__track {
  transform: translateX(-50%);
}

.ra__slide {
  flex: 0 0 25%;
  aspect-ratio: 16/9;
  position: relative;
  display: grid;
}

.ra__slide--1 {
  background: linear-gradient(135deg, #17141a, #4a3f5c);
}

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

.ra__slide--3 {
  background: linear-gradient(135deg, #2f6df6, #d6ddeb);
}

.ra__prev, .ra__next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #17141a;
  font-weight: 700;
  font-size: 20px;
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.ra__prev {
  left: 12px;
}

.ra__next {
  right: 12px;
}

.ra.is-demo .ra__viewport .ra__track {
  animation: ra-loop 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes ra-loop {
  0%, 8% {
    transform: translateX(0%);
  }
  31%, 39% {
    transform: translateX(-25%);
  }
  62%, 70% {
    transform: translateX(-50%);
  }
  92%, 100% {
    transform: translateX(-75%);
  }
}
@media (prefers-reduced-motion: reduce) {
  .ra__track {
    transition: none;
  }
  .ra.is-demo .ra__viewport .ra__track {
    animation: none !important;
  }
}

// 실제 동작은 라디오 :checked + 형제결합자로 트랙을 미는 것만으로 끝난다(0줄).
// 이 3줄은 미리보기 자동 재생만 멈춘다.
document.querySelectorAll('.ra__radio, .ra__prev, .ra__next').forEach(function (el) {
  el.addEventListener('pointerdown', function () { document.querySelector('.ra').classList.remove('is-demo'); });
});

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

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

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

const N = 3;

export default function RadioArrows({ duration = 300, easing = "cubic-bezier(.2,.8,.2,1)", color = "#ff4d1f" }: RadioArrowsProps) {
  const [active, setActive] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color, "--pos": `${-active * (100 / N)}%` };
  return (
    <div className={styles.ra} style={vars}>
      {/* 원본은 라디오 :checked + 형제결합자로 트랙을 민다(0줄 JS). 리액트 판은 같은 이동을 useState 로 대신한다 */}
      <div className={styles.viewport}>
        <div className={styles.track}>
          {[1, 2, 3].map((n) => (
            <div key={n} className={`${styles.slide} ${styles["slide" + n]}`} />
          ))}
        </div>
      </div>
      <button type="button" className={styles.prev} aria-label="이전 슬라이드" onClick={() => setActive((active - 1 + N) % N)}>‹</button>
      <button type="button" className={styles.next} aria-label="다음 슬라이드" onClick={() => setActive((active + 1) % N)}>›</button>
    </div>
  );
}