04Falling rain

<main class="stage">
  <div class="field" aria-hidden="true">
    <span class="p" style="--i:0"></span>
    <span class="p" style="--i:1"></span>
    <span class="p" style="--i:2"></span>
    <span class="p" style="--i:3"></span>
    <span class="p" style="--i:4"></span>
    <span class="p" style="--i:5"></span>
    <span class="p" style="--i:6"></span>
    <span class="p" style="--i:7"></span>
    <span class="p" style="--i:8"></span>
    <span class="p" style="--i:9"></span>
    <span class="p" style="--i:10"></span>
    <span class="p" style="--i:11"></span>
    <span class="p" style="--i:12"></span>
    <span class="p" style="--i:13"></span>
    <span class="p" style="--i:14"></span>
    <span class="p" style="--i:15"></span>
    <span class="p" style="--i:16"></span>
    <span class="p" style="--i:17"></span>
    <span class="p" style="--i:18"></span>
    <span class="p" style="--i:19"></span>
    <span class="p" style="--i:20"></span>
    <span class="p" style="--i:21"></span>
  </div>
  <p class="caption">Rainy Season Sale</p>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-base * 2;   // .6s 기준 — 빗줄기 한 번 떨어지는 시간
$easing: linear;
$color: $subject-blue;

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

.field { position: absolute; inset: 0; overflow: hidden; pointer-events: none; }

.caption {
  position: relative; z-index: 1; margin: 0;
  color: $subject-ink; font-weight: 700; font-size: clamp(16px, 5vw, 22px); line-height: 1; font-family: inherit;
}

.p {
  position: absolute;
  top: -12%;
  width: 2px; height: 22px;
  border-radius: $r-xs;
  background: linear-gradient(rgba($color, 0), $color);
  opacity: .7;
  transform: rotate(12deg);
  animation: rain $duration $easing infinite;
  animation-delay: calc(var(--i) * -0.07s);
}

@for $i from 1 through 22 {
  .p:nth-child(#{$i}) {
    left: ((($i * 37) % 96)) * 1%;
    animation-duration: $duration + ($i % 4) * .1s;
  }
}

@keyframes rain {
  0%   { transform: translateY(0) translateX(0) rotate(12deg); opacity: .7; }
  100% { transform: translateY(380px) translateX(60px) rotate(12deg); opacity: .3; }
}

// ── 접근성: 대각선 낙하를 멈추고 흐린 선만 남긴다 ────────────
@media (prefers-reduced-motion: reduce) {
  .p { animation: none; opacity: .25; top: 45%; }
}

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);
}

.field {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

.caption {
  position: relative;
  z-index: 1;
  margin: 0;
  color: #17141a;
  font-weight: 700;
  font-size: clamp(16px, 5vw, 22px);
  line-height: 1;
  font-family: inherit;
}

.p {
  position: absolute;
  top: -12%;
  width: 2px;
  height: 22px;
  border-radius: 4px;
  background: linear-gradient(rgba(47, 109, 246, 0), #2f6df6);
  opacity: 0.7;
  transform: rotate(12deg);
  animation: rain 600ms linear infinite;
  animation-delay: calc(var(--i) * -0.07s);
}

.p:nth-child(1) {
  left: 37%;
  animation-duration: 700ms;
}

.p:nth-child(2) {
  left: 74%;
  animation-duration: 800ms;
}

.p:nth-child(3) {
  left: 15%;
  animation-duration: 900ms;
}

.p:nth-child(4) {
  left: 52%;
  animation-duration: 600ms;
}

.p:nth-child(5) {
  left: 89%;
  animation-duration: 700ms;
}

.p:nth-child(6) {
  left: 30%;
  animation-duration: 800ms;
}

.p:nth-child(7) {
  left: 67%;
  animation-duration: 900ms;
}

.p:nth-child(8) {
  left: 8%;
  animation-duration: 600ms;
}

.p:nth-child(9) {
  left: 45%;
  animation-duration: 700ms;
}

.p:nth-child(10) {
  left: 82%;
  animation-duration: 800ms;
}

.p:nth-child(11) {
  left: 23%;
  animation-duration: 900ms;
}

.p:nth-child(12) {
  left: 60%;
  animation-duration: 600ms;
}

.p:nth-child(13) {
  left: 1%;
  animation-duration: 700ms;
}

.p:nth-child(14) {
  left: 38%;
  animation-duration: 800ms;
}

.p:nth-child(15) {
  left: 75%;
  animation-duration: 900ms;
}

.p:nth-child(16) {
  left: 16%;
  animation-duration: 600ms;
}

.p:nth-child(17) {
  left: 53%;
  animation-duration: 700ms;
}

.p:nth-child(18) {
  left: 90%;
  animation-duration: 800ms;
}

.p:nth-child(19) {
  left: 31%;
  animation-duration: 900ms;
}

.p:nth-child(20) {
  left: 68%;
  animation-duration: 600ms;
}

.p:nth-child(21) {
  left: 9%;
  animation-duration: 700ms;
}

.p:nth-child(22) {
  left: 46%;
  animation-duration: 800ms;
}

@keyframes rain {
  0% {
    transform: translateY(0) translateX(0) rotate(12deg);
    opacity: 0.7;
  }
  100% {
    transform: translateY(380px) translateX(60px) rotate(12deg);
    opacity: 0.3;
  }
}
@media (prefers-reduced-motion: reduce) {
  .p {
    animation: none;
    opacity: 0.25;
    top: 45%;
  }
}

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

export type RainLinesProps = {
  /** 애니메이션 기준 시간(ms) */
  duration?: number;
  /** CSS easing */
  easing?: string;
  /** 피사체 색 */
  color?: string;
};

type Vars = CSSProperties & { "--i"?: number };

const COUNT = 22;

export default function RainLines({
  duration = 600,
  easing = "linear",
  color = "#2f6df6",
}: RainLinesProps) {
  const vars = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
  } as CSSProperties;

  return (
    <div className={styles.field} style={vars} aria-hidden="true">
      {Array.from({ length: COUNT }, (_, i) => (
        <span key={i} className={styles.p} style={{ "--i": i } as Vars} />
      ))}
    </div>
  );
}