03Radio fill animation

<main class="stage">
  <fieldset class="radio-group is-demo">
    <legend class="radio-group__legend">Payment method</legend>
    <label class="radio"><input type="radio" name="pay" class="sr-input" checked><span class="radio__dot" aria-hidden="true"></span><span>Card</span></label>
    <label class="radio"><input type="radio" name="pay" class="sr-input"><span class="radio__dot" aria-hidden="true"></span><span>Bank transfer</span></label>
    <label class="radio"><input type="radio" name="pay" class="sr-input"><span class="radio__dot" aria-hidden="true"></span><span>Phone</span></label>
  </fieldset>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-quick;
$easing: $ease-out;
$color: $subject-cream;

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

.sr-input {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}

.radio-group { display: flex; flex-direction: column; gap: clamp(8px, 2.4vw, 12px); border: 0; margin: 0; padding: 0; }
.radio-group__legend {
  color: $subject-ink; font-weight: 700; font-size: 12px; line-height: 1; font-family: inherit; letter-spacing: .04em; text-transform: uppercase;
  padding: 0 0 2px;
}
.radio { display: inline-flex; align-items: center; gap: 10px; cursor: pointer;
         font-weight: 600; font-size: clamp(13px, 3.8vw, 15px); line-height: 1; font-family: inherit; color: $subject-ink; }
.radio__dot { flex: none; width: 22px; height: 22px; border-radius: 50%;
              border: 2px solid rgba($subject-cream, .6); display: grid; place-items: center; }
.radio__dot::after {
  content: ""; width: 12px; height: 12px; border-radius: 50%; background: $color;
  transform: scale(0); transition: transform $duration $easing;
}
.sr-input:checked ~ .radio__dot::after { transform: scale(1); }
.sr-input:focus-visible ~ .radio__dot { box-shadow: 0 0 0 3px rgba($subject-cream, .5); }

@media (prefers-reduced-motion: reduce) {
  // 접근성: 움직임 줄이기 설정이면 트랜지션을 즉시 끝낸다
  .radio__dot::after { transition-duration: 1ms !important; }
}

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);
}

.sr-input {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.radio-group {
  display: flex;
  flex-direction: column;
  gap: clamp(8px, 2.4vw, 12px);
  border: 0;
  margin: 0;
  padding: 0;
}

.radio-group__legend {
  color: #17141a;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0 0 2px;
}

.radio {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  font-weight: 600;
  font-size: clamp(13px, 3.8vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}

.radio__dot {
  flex: none;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  border: 2px solid rgba(255, 247, 230, 0.6);
  display: grid;
  place-items: center;
}

.radio__dot::after {
  content: "";
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #fff7e6;
  transform: scale(0);
  transition: transform 220ms ease-out;
}

.sr-input:checked ~ .radio__dot::after {
  transform: scale(1);
}

.sr-input:focus-visible ~ .radio__dot {
  box-shadow: 0 0 0 3px rgba(255, 247, 230, 0.5);
}

@media (prefers-reduced-motion: reduce) {
  .radio__dot::after {
    transition-duration: 1ms !important;
  }
}

// .is-demo 데모용 자동 순환. 실제로는 클릭이 :checked 를 바꾼다 (6줄)
document.querySelectorAll('.is-demo').forEach(function (grp) {
  var inputs = grp.querySelectorAll('.sr-input'); var i = 0;
  var t = function () { inputs[i % inputs.length].checked = true; i++; };
  t(); setInterval(t, 500);
});

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

export type RadioFillOption = { value: string; label: string };
export type RadioFillProps = {
  legend?: string;
  options?: RadioFillOption[];
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function RadioFill({
  legend = "Payment method",
  options = [
    { value: "card", label: "Card" },
    { value: "bank", label: "Bank transfer" },
    { value: "phone", label: "Phone" },
  ],
  duration = 220,
  easing = "ease-out",
  color = "#fff7e6",
}: RadioFillProps) {
  const [value, setValue] = useState(options[0]?.value);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <fieldset className={styles.group} style={vars}>
      <legend className={styles.legend}>{legend}</legend>
      {options.map((o) => (
        <label className={styles.radio} key={o.value}>
          <input
            type="radio"
            name="radio-fill"
            className={styles.srInput}
            checked={value === o.value}
            onChange={() => setValue(o.value)}
          />
          <span className={styles.dot} aria-hidden="true" />
          <span>{o.label}</span>
        </label>
      ))}
    </fieldset>
  );
}