01Falling snow

<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>
    <span class="p" style="--i:22"></span>
    <span class="p" style="--i:23"></span>
  </div>
  <p class="caption">Year-End Sale</p>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-loop * 3;   // 6s — 눈송이가 위에서 아래까지 떨어지는 기준 시간
$easing: linear;            // 일정한 속도로 낙하 (spring 은 눈에 안 맞는다)
$color: $subject-cream;

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

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

.caption {
  position: relative; z-index: 1; margin: 0;
  color: $subject-cream; font-weight: 700; font-size: clamp(16px, 5vw, 22px); line-height: 1; font-family: inherit;
  text-shadow: 0 2px 8px rgba($stage-ink, .6);
}

.p {
  position: absolute;
  top: -8%;
  left: 0;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: $color;
  opacity: 0;
  animation: fall $duration $easing infinite;
  animation-delay: calc(var(--i) * -0.28s);   // 음수 지연 — 처음부터 이미 흩어져 떨어지고 있는 것처럼
}

// nth-child 로 항목마다 다른 가로 위치·크기·속도 (SCSS 컴파일 시 고정, --i 는 지연에만 쓴다)
@for $i from 1 through 24 {
  .p:nth-child(#{$i}) {
    left: ((($i * 53) % 97)) * 1%;
    $s: 4px + ($i % 4) * 2px;
    width: $s; height: $s;
    animation-duration: $duration + ($i % 5) * .6s;
  }
}

@keyframes fall {
  0%   { transform: translateY(0) translateX(0); opacity: 0; }
  8%   { opacity: .9; }
  92%  { opacity: .85; }
  100% { transform: translateY(340px) translateX(14px); opacity: 0; }
}

// ── 접근성: 움직임 줄이기 설정이면 제자리에 흐릿하게만 ────────────
@media (prefers-reduced-motion: reduce) {
  .p { animation: none; opacity: .35; top: 40%; }
}

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);
}

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

.caption {
  position: relative;
  z-index: 1;
  margin: 0;
  color: #fff7e6;
  font-weight: 700;
  font-size: clamp(16px, 5vw, 22px);
  line-height: 1;
  font-family: inherit;
  text-shadow: 0 2px 8px rgba(23, 20, 26, 0.6);
}

.p {
  position: absolute;
  top: -8%;
  left: 0;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #fff7e6;
  opacity: 0;
  animation: fall 6s linear infinite;
  animation-delay: calc(var(--i) * -0.28s);
}

.p:nth-child(1) {
  left: 53%;
  width: 6px;
  height: 6px;
  animation-duration: 6.6s;
}

.p:nth-child(2) {
  left: 9%;
  width: 8px;
  height: 8px;
  animation-duration: 7.2s;
}

.p:nth-child(3) {
  left: 62%;
  width: 10px;
  height: 10px;
  animation-duration: 7.8s;
}

.p:nth-child(4) {
  left: 18%;
  width: 4px;
  height: 4px;
  animation-duration: 8.4s;
}

.p:nth-child(5) {
  left: 71%;
  width: 6px;
  height: 6px;
  animation-duration: 6s;
}

.p:nth-child(6) {
  left: 27%;
  width: 8px;
  height: 8px;
  animation-duration: 6.6s;
}

.p:nth-child(7) {
  left: 80%;
  width: 10px;
  height: 10px;
  animation-duration: 7.2s;
}

.p:nth-child(8) {
  left: 36%;
  width: 4px;
  height: 4px;
  animation-duration: 7.8s;
}

.p:nth-child(9) {
  left: 89%;
  width: 6px;
  height: 6px;
  animation-duration: 8.4s;
}

.p:nth-child(10) {
  left: 45%;
  width: 8px;
  height: 8px;
  animation-duration: 6s;
}

.p:nth-child(11) {
  left: 1%;
  width: 10px;
  height: 10px;
  animation-duration: 6.6s;
}

.p:nth-child(12) {
  left: 54%;
  width: 4px;
  height: 4px;
  animation-duration: 7.2s;
}

.p:nth-child(13) {
  left: 10%;
  width: 6px;
  height: 6px;
  animation-duration: 7.8s;
}

.p:nth-child(14) {
  left: 63%;
  width: 8px;
  height: 8px;
  animation-duration: 8.4s;
}

.p:nth-child(15) {
  left: 19%;
  width: 10px;
  height: 10px;
  animation-duration: 6s;
}

.p:nth-child(16) {
  left: 72%;
  width: 4px;
  height: 4px;
  animation-duration: 6.6s;
}

.p:nth-child(17) {
  left: 28%;
  width: 6px;
  height: 6px;
  animation-duration: 7.2s;
}

.p:nth-child(18) {
  left: 81%;
  width: 8px;
  height: 8px;
  animation-duration: 7.8s;
}

.p:nth-child(19) {
  left: 37%;
  width: 10px;
  height: 10px;
  animation-duration: 8.4s;
}

.p:nth-child(20) {
  left: 90%;
  width: 4px;
  height: 4px;
  animation-duration: 6s;
}

.p:nth-child(21) {
  left: 46%;
  width: 6px;
  height: 6px;
  animation-duration: 6.6s;
}

.p:nth-child(22) {
  left: 2%;
  width: 8px;
  height: 8px;
  animation-duration: 7.2s;
}

.p:nth-child(23) {
  left: 55%;
  width: 10px;
  height: 10px;
  animation-duration: 7.8s;
}

.p:nth-child(24) {
  left: 11%;
  width: 4px;
  height: 4px;
  animation-duration: 8.4s;
}

@keyframes fall {
  0% {
    transform: translateY(0) translateX(0);
    opacity: 0;
  }
  8% {
    opacity: 0.9;
  }
  92% {
    opacity: 0.85;
  }
  100% {
    transform: translateY(340px) translateX(14px);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .p {
    animation: none;
    opacity: 0.35;
    top: 40%;
  }
}

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

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

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

const COUNT = 24;

export default function SnowFall({
  duration = 6000,
  easing = "linear",
  color = "#fff7e6",
}: SnowFallProps) {
  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>
  );
}