08Wave stagger

<main class="stage">
  <div class="rows">
    <div class="bar"></div>
    <div class="bar"></div>
    <div class="bar"></div>
    <div class="bar"></div>
    <div class="bar"></div>
    <div class="bar"></div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;                            // 줄 하나가 훑는 시간 (지연은 이 값의 일부)
$easing: $ease-out;
$color: $subject-ink;                            // 막대 색 (흰 무대라 잉크 톤)

@include stage($stage-paper);

.rows {
  width: clamp(200px, 78%, 340px);
  display: grid;
  gap: clamp(8px, 2.6vw, 12px);
}

.bar {
  position: relative;
  overflow: hidden;
  height: clamp(11px, 3.2vw, 14px);
  border-radius: $r-control;
  background: rgba($color, .12);

  &::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(90deg, transparent, rgba($subject-blue, .35), transparent);
    transform: translateX(-120%);
    animation: shimmer $duration $easing infinite;
  }
}

.bar:nth-child(1) { width: 92%; }
.bar:nth-child(2) { width: 68%; }
.bar:nth-child(3) { width: 84%; }
.bar:nth-child(4) { width: 55%; }
.bar:nth-child(5) { width: 78%; }
.bar:nth-child(6) { width: 45%; }

// 줄마다 60ms 씩 늦게 시작해 파도처럼 보인다. 음수 지연 = 렌더 첫 프레임부터 이미 진행 중
@for $i from 1 through 6 {
  .bar:nth-child(#{$i})::after { animation-delay: -($i - 1) * 60ms; }
}

// 짝수 줄은 반대 방향으로 훑어 파도가 갈라지는 느낌을 준다
.bar:nth-child(even)::after { animation-name: shimmer-reverse; }

@keyframes shimmer {
  to { transform: translateX(120%); }
}
@keyframes shimmer-reverse {
  from { transform: translateX(120%); }
  to   { transform: translateX(-120%); }
}

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

.rows {
  width: clamp(200px, 78%, 340px);
  display: grid;
  gap: clamp(8px, 2.6vw, 12px);
}

.bar {
  position: relative;
  overflow: hidden;
  height: clamp(11px, 3.2vw, 14px);
  border-radius: 12px;
  background: rgba(23, 20, 26, 0.12);
}
.bar::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(47, 109, 246, 0.35), transparent);
  transform: translateX(-120%);
  animation: shimmer 2s ease-out infinite;
}

.bar:nth-child(1) {
  width: 92%;
}

.bar:nth-child(2) {
  width: 68%;
}

.bar:nth-child(3) {
  width: 84%;
}

.bar:nth-child(4) {
  width: 55%;
}

.bar:nth-child(5) {
  width: 78%;
}

.bar:nth-child(6) {
  width: 45%;
}

.bar:nth-child(1)::after {
  animation-delay: -0ms;
}

.bar:nth-child(2)::after {
  animation-delay: -60ms;
}

.bar:nth-child(3)::after {
  animation-delay: -120ms;
}

.bar:nth-child(4)::after {
  animation-delay: -180ms;
}

.bar:nth-child(5)::after {
  animation-delay: -240ms;
}

.bar:nth-child(6)::after {
  animation-delay: -300ms;
}

.bar:nth-child(even)::after {
  animation-name: shimmer-reverse;
}

@keyframes shimmer {
  to {
    transform: translateX(120%);
  }
}
@keyframes shimmer-reverse {
  from {
    transform: translateX(120%);
  }
  to {
    transform: translateX(-120%);
  }
}
@media (prefers-reduced-motion: reduce) {
  .bar::after {
    animation: none !important;
    opacity: 0.4;
    transform: translateX(0);
  }
}

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

export type WaveStaggerSkeletonProps = {
  duration?: number;
  easing?: string;
  color?: string;
  /** 줄 수 (기본 6) */
  rows?: number;
  /** 줄 사이 시차 (기본 60ms) */
  stagger?: number;
  className?: string;
};

const WIDTHS = ["92%", "68%", "84%", "55%", "78%", "45%"];

export default function WaveStaggerSkeleton({
  duration = 2000,
  easing = "ease-out",
  color = "#2f6df6",
  rows = 6,
  stagger = 60,
  className = "",
}: WaveStaggerSkeletonProps) {
  const vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color } as CSSProperties;
  return (
    <div className={`${styles.rows} ${className}`} style={vars}>
      {Array.from({ length: rows }).map((_, i) => (
        <div
          key={i}
          className={styles.bar}
          style={{
            width: WIDTHS[i % WIDTHS.length],
            animationDelay: `${-i * stagger}ms`,
            animationDirection: i % 2 ? "reverse" : "normal",
          } as CSSProperties}
        />
      ))}
    </div>
  );
}