06Color-fill background

<main class="stage">
  <label class="switch is-demo">
    <input type="checkbox" class="switch__input" role="switch">
    <span class="switch__track">
      <span class="switch__fill"></span>
      <span class="switch__knob"></span>
    </span>
    <span class="switch__label">Premium plan</span>
  </label>
</main>

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

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

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

.switch {
  position: relative;
  display: inline-flex; align-items: center; gap: clamp(10px, 3vw, 14px);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.switch__input {
  position: absolute; inset: 0; width: 100%; height: 100%;
  margin: 0; opacity: 0; cursor: pointer;
}
.switch__track {
  position: relative; overflow: hidden;
  width: clamp(48px, 13vw, 56px); height: clamp(26px, 7vw, 30px);
  border-radius: $r-pill;
  background: rgba(23, 20, 26, .18);
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, .15);
  transition: box-shadow $duration $easing;
}
.switch__fill {
  position: absolute; inset: 0;
  background: $color;
  clip-path: circle(0% at 18% 50%);
  transition: clip-path $duration $easing;
}
.switch__knob {
  position: absolute; top: 3px; left: 3px; z-index: 1;
  width: clamp(20px, 5.5vw, 24px); height: clamp(20px, 5.5vw, 24px);
  border-radius: 50%;
  background: $stage-paper;
  box-shadow: $shadow-press;
  transform: translateX(0);
  transition: transform $duration cubic-bezier(0.34, 1.56, 0.64, 1);
}
.switch__label { color: $subject-ink; font-weight: 600; font-size: clamp(14px, 4vw, 17px); line-height: 1; font-family: inherit; }

// ── 실제 동작: 노브가 지나간 자리부터 clip-path 원이 번진다 ──────
.switch__input:checked ~ .switch__track .switch__fill { clip-path: circle(75% at 82% 50%); }
.switch__input:checked ~ .switch__track .switch__knob  { transform: translateX(clamp(22px, 6vw, 26px)); }
.switch__input:checked ~ .switch__track { box-shadow: inset 0 3px 8px rgba(0, 0, 0, .28); }

.switch__input:focus-visible ~ .switch__track {
  outline: 2px solid $subject-ink; outline-offset: 3px;
}

// ── 데모 루프 ─────────────────────────────
// 한 겹: 노브는 도착 지점을 지나쳤다 찌그러지며 안착하고(스프링+squash),
//        트랙 내부 그림자가 채워지는 순간 깊어졌다 얕아진다(바닥에 앉는 깊이).
.switch.is-demo .switch__fill  { animation: fill-loop $dur-loop $easing infinite; }
.switch.is-demo .switch__knob  { animation: knob-spring-loop $dur-loop $easing infinite; }
.switch.is-demo .switch__track { animation: shadow-depth-loop $dur-loop $easing infinite; }

@keyframes fill-loop {
  0%, 15%   { clip-path: circle(0% at 18% 50%); }
  40%, 60%  { clip-path: circle(75% at 82% 50%); }
  85%, 100% { clip-path: circle(0% at 18% 50%); }
}
@keyframes knob-loop {
  0%, 15%   { transform: translateX(0); }
  40%, 60%  { transform: translateX(26px); }
  85%, 100% { transform: translateX(0); }
}
@keyframes knob-spring-loop {
  0%, 15%   { transform: translateX(0) scaleX(1) scaleY(1); }
  38%       { transform: translateX(29px) scaleX(1.25) scaleY(.85); }  // 오버슈트 + 도착 순간 squash
  43%       { transform: translateX(25px) scaleX(1.08) scaleY(.94); }  // 되튕기며 회복
  47%, 60%  { transform: translateX(26px) scaleX(1) scaleY(1); }       // 안착
  84%       { transform: translateX(-2px) scaleX(.92) scaleY(1.06); }  // 출발 반동
  85%, 100% { transform: translateX(0) scaleX(1) scaleY(1); }
}
@keyframes shadow-depth-loop {
  0%, 15%   { box-shadow: inset 0 1px 3px rgba(0, 0, 0, .15); }
  38%       { box-shadow: inset 0 3px 8px rgba(0, 0, 0, .28); }
  40%, 60%  { box-shadow: inset 0 3px 8px rgba(0, 0, 0, .28); }
  85%, 100% { box-shadow: inset 0 1px 3px rgba(0, 0, 0, .15); }
}

@media (prefers-reduced-motion: reduce) {
  .switch.is-demo .switch__fill, .switch.is-demo .switch__knob,
  .switch.is-demo .switch__track { animation: none !important; }
  .switch__fill, .switch__knob { transition: none; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.switch {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: clamp(10px, 3vw, 14px);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.switch__input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  opacity: 0;
  cursor: pointer;
}

.switch__track {
  position: relative;
  overflow: hidden;
  width: clamp(48px, 13vw, 56px);
  height: clamp(26px, 7vw, 30px);
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.18);
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.15);
  transition: box-shadow 300ms ease-out;
}

.switch__fill {
  position: absolute;
  inset: 0;
  background: #17141a;
  clip-path: circle(0% at 18% 50%);
  transition: clip-path 300ms ease-out;
}

.switch__knob {
  position: absolute;
  top: 3px;
  left: 3px;
  z-index: 1;
  width: clamp(20px, 5.5vw, 24px);
  height: clamp(20px, 5.5vw, 24px);
  border-radius: 50%;
  background: #ffffff;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  transform: translateX(0);
  transition: transform 300ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

.switch__label {
  color: #17141a;
  font-weight: 600;
  font-size: clamp(14px, 4vw, 17px);
  line-height: 1;
  font-family: inherit;
}

.switch__input:checked ~ .switch__track .switch__fill {
  clip-path: circle(75% at 82% 50%);
}

.switch__input:checked ~ .switch__track .switch__knob {
  transform: translateX(clamp(22px, 6vw, 26px));
}

.switch__input:checked ~ .switch__track {
  box-shadow: inset 0 3px 8px rgba(0, 0, 0, 0.28);
}

.switch__input:focus-visible ~ .switch__track {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.switch.is-demo .switch__fill {
  animation: fill-loop 2s ease-out infinite;
}

.switch.is-demo .switch__knob {
  animation: knob-spring-loop 2s ease-out infinite;
}

.switch.is-demo .switch__track {
  animation: shadow-depth-loop 2s ease-out infinite;
}

@keyframes fill-loop {
  0%, 15% {
    clip-path: circle(0% at 18% 50%);
  }
  40%, 60% {
    clip-path: circle(75% at 82% 50%);
  }
  85%, 100% {
    clip-path: circle(0% at 18% 50%);
  }
}
@keyframes knob-loop {
  0%, 15% {
    transform: translateX(0);
  }
  40%, 60% {
    transform: translateX(26px);
  }
  85%, 100% {
    transform: translateX(0);
  }
}
@keyframes knob-spring-loop {
  0%, 15% {
    transform: translateX(0) scaleX(1) scaleY(1);
  }
  38% {
    transform: translateX(29px) scaleX(1.25) scaleY(0.85);
  }
  43% {
    transform: translateX(25px) scaleX(1.08) scaleY(0.94);
  }
  47%, 60% {
    transform: translateX(26px) scaleX(1) scaleY(1);
  }
  84% {
    transform: translateX(-2px) scaleX(0.92) scaleY(1.06);
  }
  85%, 100% {
    transform: translateX(0) scaleX(1) scaleY(1);
  }
}
@keyframes shadow-depth-loop {
  0%, 15% {
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.15);
  }
  38% {
    box-shadow: inset 0 3px 8px rgba(0, 0, 0, 0.28);
  }
  40%, 60% {
    box-shadow: inset 0 3px 8px rgba(0, 0, 0, 0.28);
  }
  85%, 100% {
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.15);
  }
}
@media (prefers-reduced-motion: reduce) {
  .switch.is-demo .switch__fill, .switch.is-demo .switch__knob,
  .switch.is-demo .switch__track {
    animation: none !important;
  }
  .switch__fill, .switch__knob {
    transition: none;
  }
}

document.querySelectorAll(".switch").forEach(function (s) {
  var input = s.querySelector(".switch__input");
  var sync = function () { input.setAttribute("aria-checked", String(input.checked)); };
  input.addEventListener("pointerdown", function () { s.classList.remove("is-demo"); });
  input.addEventListener("change", sync);
  sync();
});

import { useState } from "react";
import type { ChangeEvent, CSSProperties } from "react";
import styles from "./ColorFillToggle.module.scss";

export type ColorFillToggleProps = {
  label?: string;
  duration?: number;
  easing?: string;
  color?: string;
  defaultChecked?: boolean;
  onChange?: (checked: boolean) => void;
};

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

export default function ColorFillToggle({
  label = "프리미엄 플랜",
  duration = 300,
  easing = "ease-out",
  color = "#17141a",
  defaultChecked = false,
  onChange,
}: ColorFillToggleProps) {
  const [checked, setChecked] = useState(defaultChecked);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <label className={styles.switch} style={vars}>
      <input
        type="checkbox"
        role="switch"
        aria-checked={checked}
        className={styles.switch__input}
        checked={checked}
        onChange={(e: ChangeEvent<HTMLInputElement>) => { setChecked(e.target.checked); onChange?.(e.target.checked); }}
      />
      <span className={styles.switch__track}>
        <span className={styles.switch__fill} />
        <span className={styles.switch__knob} />
      </span>
      <span className={styles.switch__label}>{label}</span>
    </label>
  );
}