09Rainbow text cycle

<main class="stage">
  <h1 class="rainbow">The Festival Begins</h1>
</main>

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

$duration: $dur-loop;                              // 색상환이 360도 한 바퀴 도는 시간
$easing: linear;
$color: $subject-blue;                              // 그러데이션의 시작 색

@include stage($stage-ink);

.rainbow {
  margin: 0;
  font-weight: 800; font-size: clamp(28px, 8.6vw, 46px); line-height: 1.2; font-family: inherit;
  text-align: center;
  background: linear-gradient(90deg, $color, $stage-yellow, $stage-orange, $error, $subject-cream, $color);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
  animation: hue-cycle $duration $easing infinite;    // 위치가 아니라 색상환 자체를 돌린다
}

@keyframes hue-cycle {
  from { filter: hue-rotate(0deg); }
  to   { filter: hue-rotate(360deg); }
}

@media (prefers-reduced-motion: reduce) {
  .rainbow { animation: none; filter: hue-rotate(0deg); }
}

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);
}

.rainbow {
  margin: 0;
  font-weight: 800;
  font-size: clamp(28px, 8.6vw, 46px);
  line-height: 1.2;
  font-family: inherit;
  text-align: center;
  background: linear-gradient(90deg, #2f6df6, #ffd23f, #ff4d1f, #c2361a, #fff7e6, #2f6df6);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
  animation: hue-cycle 2s linear infinite;
}

@keyframes hue-cycle {
  from {
    filter: hue-rotate(0deg);
  }
  to {
    filter: hue-rotate(360deg);
  }
}
@media (prefers-reduced-motion: reduce) {
  .rainbow {
    animation: none;
    filter: hue-rotate(0deg);
  }
}

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

export type RainbowTextProps = {
  text: string;
  /** 색상환이 360도 한 바퀴 도는 시간 (기본 2000ms) */
  duration?: number;
  easing?: string;
  /** 그러데이션 시작 색 */
  color?: string;
};

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

export default function RainbowText({
  text,
  duration = 2000,
  easing = "linear",
  color = "#2f6df6",
}: RainbowTextProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return <h1 className={styles.rainbow} style={vars}>{text}</h1>;
}