08Color sweep

<main class="stage">
  <span class="badge">Limited-time deal</span>
</main>

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

// ── 변수 3개 ─────────────────────────────
$duration: $dur-loop;
$easing: linear;               // 이음새 없이 계속 도는 스윕이라 등속이 맞다
$color: $subject-cream;        // 빛 줄기 색

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

.badge {
  position: relative;
  overflow: hidden;
  display: inline-block;
  padding: $sp-2 $sp-5;
  border-radius: $r-pill;
  background: color-mix(in srgb, $stage-ink 30%, $stage-orange);
  color: $subject-cream;
  font-weight: 700;
  font-size: clamp(16px, 4.6vw, 22px);
  line-height: 1;
  font-family: inherit;

  // 대각선 그러데이션을 폭 250% 로 깔고 background-position 을 끝없이 옮긴다 (linear·infinite → 이음새 없음)
  &::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(115deg, transparent 30%, $color 48%, transparent 66%);
    background-size: 250% 100%;
    mix-blend-mode: overlay;
    animation: sweep $duration $easing infinite, sweep-thick $duration $easing infinite;
  }
}

@keyframes sweep {
  0%   { background-position: 150% 0; }
  100% { background-position: -150% 0; }
}

// 페인트 물성: 스윕 줄기의 수직 두께가 불규칙 요동 — inset 진동 (transform 아님, 병렬 안전)
@keyframes sweep-thick {
  0%   { inset: 0 -1px; }
  14%  { inset: 1px 0; }
  28%  { inset: -1px 1px; }
  42%  { inset: 0.5px -0.5px; }
  57%  { inset: -0.5px 1px; }
  71%  { inset: 1px 0.5px; }
  85%  { inset: -1px -0.5px; }
  100% { inset: 0 -1px; }
}

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

.badge {
  position: relative;
  overflow: hidden;
  display: inline-block;
  padding: 8px 20px;
  border-radius: 999px;
  background: color-mix(in srgb, #17141a 30%, #ff4d1f);
  color: #fff7e6;
  font-weight: 700;
  font-size: clamp(16px, 4.6vw, 22px);
  line-height: 1;
  font-family: inherit;
}
.badge::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(115deg, transparent 30%, #fff7e6 48%, transparent 66%);
  background-size: 250% 100%;
  mix-blend-mode: overlay;
  animation: sweep 2s linear infinite, sweep-thick 2s linear infinite;
}

@keyframes sweep {
  0% {
    background-position: 150% 0;
  }
  100% {
    background-position: -150% 0;
  }
}
@keyframes sweep-thick {
  0% {
    inset: 0 -1px;
  }
  14% {
    inset: 1px 0;
  }
  28% {
    inset: -1px 1px;
  }
  42% {
    inset: 0.5px -0.5px;
  }
  57% {
    inset: -0.5px 1px;
  }
  71% {
    inset: 1px 0.5px;
  }
  85% {
    inset: -1px -0.5px;
  }
  100% {
    inset: 0 -1px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .badge::after {
    animation: none;
    opacity: 0;
  }
}

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

export type ColorSweepBadgeProps = {
  children: ReactNode;
  /** 빛 한 줄이 한 바퀴 도는 시간 (기본 2000ms) */
  duration?: number;
  /** 배지 바탕색 */
  bg?: string;
  /** 빛 줄기 색 */
  color?: string;
};

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

export default function ColorSweepBadge({
  children,
  duration = 2000,
  bg = "#ff4d1f",
  color = "#fff7e6",
}: ColorSweepBadgeProps) {
  const vars: Vars = {
    "--duration": `${duration}ms`,
    "--bg": bg,
    "--color": color,
  };
  return (
    <span className={styles.badge} style={vars}>
      {children}
    </span>
  );
}