03Aurora blur

<main class="stage">
  <span class="aurora a1" aria-hidden="true"></span>
  <span class="aurora a2" aria-hidden="true"></span>
  <span class="aurora a3" aria-hidden="true"></span>
  <p class="hint">Dark hero</p>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;                                // 덩어리 하나가 경로를 한 바퀴 도는 시간
$easing: $ease-out;
$color: $subject-blue;                                // 덩어리 색 하나

// ── 데모 무대 ──────────────────────────────────────────
@include stage($stage-orange);

.stage {
  position: relative;
  overflow: hidden;
}

// filter: blur 로 흐린 덩어리를 겹치고, transform(translate·rotate)으로만 움직인다
.aurora {
  position: absolute;
  width: 38%;
  aspect-ratio: 1;
  border-radius: 50%;
  filter: blur(3px);
  opacity: 1;
}

.a1 { background: radial-gradient($subject-cream 0%, $subject-cream 25%, transparent 55%); top: -8%; left: 8%; animation: spin1 $duration linear infinite; }
.a2 { background: radial-gradient($stage-ink 0%, $stage-ink 25%, transparent 55%); bottom: -12%; right: 4%; animation: spin2 $duration linear infinite; animation-delay: -1s; }
.a3 { background: radial-gradient($color 0%, $color 25%, transparent 55%); top: 22%; right: 28%; animation: spin3 $duration linear infinite; animation-delay: -.5s; }

@keyframes spin1 { 0% { transform: translate(0, 0) rotate(0deg); } 50% { transform: translate(56px, 38px) rotate(180deg); } 100% { transform: translate(0, 0) rotate(360deg); } }
@keyframes spin2 { 0% { transform: translate(0, 0) rotate(0deg); } 50% { transform: translate(-50px, -30px) rotate(-160deg); } 100% { transform: translate(0, 0) rotate(-360deg); } }
@keyframes spin3 { 0% { transform: translate(0, 0) rotate(0deg); } 50% { transform: translate(36px, -48px) rotate(150deg); } 100% { transform: translate(0, 0) rotate(300deg); } }

.hint {
  position: relative;
  margin: 0;
  padding: 10px 20px;
  border-radius: $r-pill;
  background: rgba($stage-ink, .3);
  color: $stage-paper;
  font: 700 clamp(14px, 4vw, 18px)/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  .aurora { animation: none; }
}

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);
}

.stage {
  position: relative;
  overflow: hidden;
}

.aurora {
  position: absolute;
  width: 38%;
  aspect-ratio: 1;
  border-radius: 50%;
  filter: blur(3px);
  opacity: 1;
}

.a1 {
  background: radial-gradient(#fff7e6 0%, #fff7e6 25%, transparent 55%);
  top: -8%;
  left: 8%;
  animation: spin1 2s linear infinite;
}

.a2 {
  background: radial-gradient(#17141a 0%, #17141a 25%, transparent 55%);
  bottom: -12%;
  right: 4%;
  animation: spin2 2s linear infinite;
  animation-delay: -1s;
}

.a3 {
  background: radial-gradient(#2f6df6 0%, #2f6df6 25%, transparent 55%);
  top: 22%;
  right: 28%;
  animation: spin3 2s linear infinite;
  animation-delay: -0.5s;
}

@keyframes spin1 {
  0% {
    transform: translate(0, 0) rotate(0deg);
  }
  50% {
    transform: translate(56px, 38px) rotate(180deg);
  }
  100% {
    transform: translate(0, 0) rotate(360deg);
  }
}
@keyframes spin2 {
  0% {
    transform: translate(0, 0) rotate(0deg);
  }
  50% {
    transform: translate(-50px, -30px) rotate(-160deg);
  }
  100% {
    transform: translate(0, 0) rotate(-360deg);
  }
}
@keyframes spin3 {
  0% {
    transform: translate(0, 0) rotate(0deg);
  }
  50% {
    transform: translate(36px, -48px) rotate(150deg);
  }
  100% {
    transform: translate(0, 0) rotate(300deg);
  }
}
.hint {
  position: relative;
  margin: 0;
  padding: 10px 20px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.3);
  color: #ffffff;
  font: 700 clamp(14px, 4vw, 18px)/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  .aurora {
    animation: none;
  }
}

import type { CSSProperties, ReactNode } from "react";
import styles from "./AuroraBlurBg.module.scss";

export type AuroraBlurBgProps = {
  children?: ReactNode;
  /** 덩어리 하나가 경로를 한 바퀴 도는 시간 (기본 2000ms) */
  duration?: number;
  easing?: string;
  /** 덩어리 색 하나 */
  color?: string;
  className?: string;
};

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

export default function AuroraBlurBg({
  children,
  duration = 2000,
  easing = "linear",
  color = "#2f6df6",
  className = "",
}: AuroraBlurBgProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--color": color };
  void easing; // linear 고정 — spin 키프레임은 등속이 자연스럽다
  return (
    <div className={`${styles.stage} ${className}`} style={vars}>
      <span className={`${styles.aurora} ${styles.a1}`} aria-hidden="true" />
      <span className={`${styles.aurora} ${styles.a2}`} aria-hidden="true" />
      <span className={`${styles.aurora} ${styles.a3}`} aria-hidden="true" />
      {children}
    </div>
  );
}