07Nhịp độ nhanh chậm

<main class="stage">
  <div class="marquee">
    <div class="marquee__track">
      <span class="marquee__chip"></span>
      <span class="marquee__chip"></span>
      <span class="marquee__chip"></span>
      <span class="marquee__chip"></span>
      <span class="marquee__chip"></span>
      <span class="marquee__chip" aria-hidden="true"></span>
      <span class="marquee__chip" aria-hidden="true"></span>
      <span class="marquee__chip" aria-hidden="true"></span>
      <span class="marquee__chip" aria-hidden="true"></span>
      <span class="marquee__chip" aria-hidden="true"></span>
    </div>
  </div>
</main>

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

$duration: $dur-loop;
$easing: cubic-bezier(.65, 0, .35, 1);              // 비선형 — 이음매 근처는 느리고 중간은 빠르다
$color: $subject-cream;

@include stage($stage-orange);

.marquee {
  width: min(300px, 80vw);
  overflow: hidden;
}
.marquee__track {
  display: flex;
  width: max-content;
  animation: marquee-scroll $duration $easing infinite;
}
.marquee__chip {
  margin-right: 22px;   // 트랙의 gap 대신 — 세트 폭이 정확히 절반이 되어 -50% 이음새가 0px 이 된다
  flex-shrink: 0;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: $color;
}

// linear 대신 커스텀 cubic-bezier 를 타이밍 함수로 써도 -50% 이동량은 그대로다.
// 이음매(0%·100%)에선 느리게 붙고 구간 중간에서 빨라지는 리듬만 달라진다 — JS 없이, 한 줄로
@keyframes marquee-scroll {
  from { transform: translateX(0); }
  to   { transform: translateX(-50%); }
}

@media (prefers-reduced-motion: reduce) {
  .marquee__track { animation: none; 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: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.marquee {
  width: min(300px, 80vw);
  overflow: hidden;
}

.marquee__track {
  display: flex;
  width: max-content;
  animation: marquee-scroll 2s cubic-bezier(0.65, 0, 0.35, 1) infinite;
}

.marquee__chip {
  margin-right: 22px;
  flex-shrink: 0;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: #fff7e6;
}

@keyframes marquee-scroll {
  from {
    transform: translateX(0);
  }
  to {
    transform: translateX(-50%);
  }
}
@media (prefers-reduced-motion: reduce) {
  .marquee__track {
    animation: none;
    transform: translateX(0);
  }
}

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

export type VariableSpeedMarqueeProps = {
  count?: number;
  duration?: number;
  /** 비선형 타이밍 함수 — 이음매 근처는 느리고 가운데는 빠르다 */
  easing?: string;
  color?: string;
};

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

export default function VariableSpeedMarquee({
  count = 5,
  duration = 9000,
  easing = "cubic-bezier(.65,0,.35,1)",
  color = "#fff7e6",
}: VariableSpeedMarqueeProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  const dots = Array.from({ length: count * 2 });

  return (
    <div className={styles.marquee} style={vars}>
      <div className={styles.track}>
        {dots.map((_, i) => (
          <span key={i} className={styles.chip} aria-hidden={i >= count} />
        ))}
      </div>
    </div>
  );
}