01Đếm số nguyên bằng @property

<main class="stage">
  <div class="counter is-demo">
    <span class="counter__num" aria-hidden="true"></span>
    <span class="counter__sr">12,480</span>
    <span class="counter__label">Người đăng ký</span>
  </div>
</main>

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

// ── 변수 3개. 변형은 이것만 바꾼다 ──────────────────────────
$duration: $dur-loop;                              // 0에서 목표까지 세는 시간
$easing: $ease-out;
$color: $subject-cream;                             // 숫자 색

@include stage($stage-ink);

// ── @property: 정수 커스텀 속성이라야 애니메이션 중간값도 정수로 보간된다 ──
@property --num {
  syntax: '<integer>';
  initial-value: 0;
  inherits: false;
}

.counter {
  text-align: center;

  &__num {
    --num: 0;
    counter-reset: num var(--num);
    display: block;
    font-weight: 800; font-size: clamp(36px, 11vw, 60px); line-height: 1; font-family: inherit;
    font-variant-numeric: tabular-nums;              // 자릿수가 늘어도 숫자 폭이 흔들리지 않는다
    color: $color;

    &::before { content: counter(num); }
  }

  // counter() 생성 콘텐츠는 스크린 리더가 못 읽는다 — 실제 최종값을 시각적으로만 숨겨 따로 둔다
  &__sr {
    position: absolute;
    width: 1px; height: 1px;
    overflow: hidden;
    clip-path: inset(50%);
    white-space: nowrap;
  }

  &__label {
    display: block;
    margin-top: clamp(6px, 2vw, 10px);
    font-weight: 600; font-size: clamp(12px, 3.4vw, 15px); line-height: 1; font-family: inherit;
    color: rgba(255, 255, 255, .6);
  }
}

.counter.is-demo .counter__num {
  animation: count-up $duration $easing infinite;
}

@keyframes count-up {
  0%   { --num: 0; }
  65%  { --num: 12480; }
  100% { --num: 12480; }
}

// ── 접근성: 움직임 줄이기 설정이면 최종값에 즉시 멈춘다 ──────────
@media (prefers-reduced-motion: reduce) {
  .counter.is-demo .counter__num { animation: none; --num: 12480; }
}

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);
}

@property --num {
  syntax: "<integer>";
  initial-value: 0;
  inherits: false;
}
.counter {
  text-align: center;
}
.counter__num {
  --num: 0;
  counter-reset: num var(--num);
  display: block;
  font-weight: 800;
  font-size: clamp(36px, 11vw, 60px);
  line-height: 1;
  font-family: inherit;
  font-variant-numeric: tabular-nums;
  color: #fff7e6;
}
.counter__num::before {
  content: counter(num);
}
.counter__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
.counter__label {
  display: block;
  margin-top: clamp(6px, 2vw, 10px);
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: rgba(255, 255, 255, 0.6);
}

.counter.is-demo .counter__num {
  animation: count-up 2s ease-out infinite;
}

@keyframes count-up {
  0% {
    --num: 0;
  }
  65% {
    --num: 12480;
  }
  100% {
    --num: 12480;
  }
}
@media (prefers-reduced-motion: reduce) {
  .counter.is-demo .counter__num {
    animation: none;
    --num: 12480;
  }
}

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

export type CountUpPropertyProps = {
  value: number;
  label: string;
  /** 0에서 목표값까지 세는 시간 (기본 2000ms) */
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string; "--num-target"?: number };

export default function CountUpProperty({ value, label, duration = 2000, easing = "ease-out", color = "#fff7e6" }: CountUpPropertyProps) {
  const vars: Vars = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
    "--num-target": value,
  };

  return (
    <div className={styles.counter} style={vars}>
      <span className={styles.num} aria-hidden="true" />
      <span className={styles.sr}>{value.toLocaleString()}</span>
      <span className={styles.label}>{label}</span>
    </div>
  );
}