01iOS pill segmented control

<main class="stage">
  <fieldset class="seg is-demo">
    <legend class="sr-only">Status filter</legend>
    <input type="radio" name="seg1" id="seg1-1" class="seg__radio" checked>
    <input type="radio" name="seg1" id="seg1-2" class="seg__radio">
    <input type="radio" name="seg1" id="seg1-3" class="seg__radio">
    <div class="seg__track">
      <span class="seg__pill" aria-hidden="true"></span>
      <label class="seg__tab" for="seg1-1">All</label>
      <label class="seg__tab" for="seg1-2">Active</label>
      <label class="seg__tab" for="seg1-3">Done</label>
    </div>
  </fieldset>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-quick;
$easing: $ease-pop;
$color: $subject-blue;
$ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);

@include stage($stage-ink);

.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;
}
.seg { border: 0; margin: 0; padding: 0; width: min(280px, 84vw); }
.seg__radio { position: absolute; opacity: 0; pointer-events: none; width: 1px; height: 1px; }

.seg__track {
  position: relative;
  display: flex;
  gap: 0;
  padding: $sp-1;
  background: rgba($subject-cream, .14);
  border-radius: $r-pill;
}
.seg__tab {
  position: relative; z-index: 1;
  flex: 1 1 0;
  text-align: center;
  padding: $sp-2 $sp-1;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: rgba($subject-cream, .55);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: color $duration $easing;
}
.seg__pill {
  position: absolute; top: $sp-1; left: $sp-1; bottom: $sp-1;
  width: calc((100% - #{$sp-1} * 2) / 3);
  border-radius: $r-pill;
  background: $color;
  transform: translateX(0);
  transform-origin: center;
  transition: transform $duration $ease-bounce;
}

// ── 실제 동작: :checked 만으로 필이 균등폭 구간을 옮겨가고, 선택된 라벨만 밝아진다 ──────────────
#seg1-2:checked ~ .seg__track .seg__pill { transform: translateX(100%); }
#seg1-3:checked ~ .seg__track .seg__pill { transform: translateX(200%); }
#seg1-1:checked ~ .seg__track .seg__tab:nth-child(2) { color: $subject-cream; }
#seg1-2:checked ~ .seg__track .seg__tab:nth-child(3) { color: $subject-cream; }
#seg1-3:checked ~ .seg__track .seg__tab:nth-child(4) { color: $subject-cream; }

// ── 데모 루프: 클릭 전까지 세 칸을 스스로 오간다 ──────────────
.seg.is-demo .seg__pill { animation: seg-loop-jelly $dur-loop $easing infinite; }
@keyframes seg-loop {
  0%, 15%  { transform: translateX(0); }
  33%, 48% { transform: translateX(100%); }
  66%, 81% { transform: translateX(200%); }
  100%     { transform: translateX(0); }
}
// 젤리 스트레치 + 스프링 오버슛 보강: 정지 구간 값은 seg-loop 과 동일, 이동 구간에 scaleX·도착 오버슛 삽입
@keyframes seg-loop-jelly {
  0%, 15%  { transform: translateX(0%) scaleX(1); }
  22%      { transform: translateX(58%) scaleX(1.25); }
  30%      { transform: translateX(103%) scaleX(1.05); }
  33%, 48% { transform: translateX(100%) scaleX(1); }
  55%      { transform: translateX(158%) scaleX(1.25); }
  63%      { transform: translateX(203%) scaleX(1.05); }
  66%, 81% { transform: translateX(200%) scaleX(1); }
  88%      { transform: translateX(92%) scaleX(1.25); }
  96%      { transform: translateX(-3%) scaleX(1.05); }
  100%     { transform: translateX(0%) scaleX(1); }
}

@media (prefers-reduced-motion: reduce) {
  .seg__pill { transition: none; }
  .seg.is-demo .seg__pill { animation: none !important; }
}

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);
}

.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;
}

.seg {
  border: 0;
  margin: 0;
  padding: 0;
  width: min(280px, 84vw);
}

.seg__radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
  width: 1px;
  height: 1px;
}

.seg__track {
  position: relative;
  display: flex;
  gap: 0;
  padding: 4px;
  background: rgba(255, 247, 230, 0.14);
  border-radius: 999px;
}

.seg__tab {
  position: relative;
  z-index: 1;
  flex: 1 1 0;
  text-align: center;
  padding: 8px 4px;
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 14px);
  line-height: 1;
  font-family: inherit;
  color: rgba(255, 247, 230, 0.55);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: color 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}

.seg__pill {
  position: absolute;
  top: 4px;
  left: 4px;
  bottom: 4px;
  width: calc((100% - 4px * 2) / 3);
  border-radius: 999px;
  background: #2f6df6;
  transform: translateX(0);
  transform-origin: center;
  transition: transform 220ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

#seg1-2:checked ~ .seg__track .seg__pill {
  transform: translateX(100%);
}

#seg1-3:checked ~ .seg__track .seg__pill {
  transform: translateX(200%);
}

#seg1-1:checked ~ .seg__track .seg__tab:nth-child(2) {
  color: #fff7e6;
}

#seg1-2:checked ~ .seg__track .seg__tab:nth-child(3) {
  color: #fff7e6;
}

#seg1-3:checked ~ .seg__track .seg__tab:nth-child(4) {
  color: #fff7e6;
}

.seg.is-demo .seg__pill {
  animation: seg-loop-jelly 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

@keyframes seg-loop {
  0%, 15% {
    transform: translateX(0);
  }
  33%, 48% {
    transform: translateX(100%);
  }
  66%, 81% {
    transform: translateX(200%);
  }
  100% {
    transform: translateX(0);
  }
}
@keyframes seg-loop-jelly {
  0%, 15% {
    transform: translateX(0%) scaleX(1);
  }
  22% {
    transform: translateX(58%) scaleX(1.25);
  }
  30% {
    transform: translateX(103%) scaleX(1.05);
  }
  33%, 48% {
    transform: translateX(100%) scaleX(1);
  }
  55% {
    transform: translateX(158%) scaleX(1.25);
  }
  63% {
    transform: translateX(203%) scaleX(1.05);
  }
  66%, 81% {
    transform: translateX(200%) scaleX(1);
  }
  88% {
    transform: translateX(92%) scaleX(1.25);
  }
  96% {
    transform: translateX(-3%) scaleX(1.05);
  }
  100% {
    transform: translateX(0%) scaleX(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .seg__pill {
    transition: none;
  }
  .seg.is-demo .seg__pill {
    animation: none !important;
  }
}

// .is-demo 자동 순환 (실제 클릭이 오면 멈춘다, 7줄)
var seg = document.querySelector('.seg');
var radios = seg.querySelectorAll('.seg__radio'); var i = 0;
var t = setInterval(function () { radios[i % radios.length].checked = true; i++; }, 700);
radios.forEach(function (r) { r.addEventListener('pointerdown', function () { seg.classList.remove('is-demo'); clearInterval(t); }); });

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

export type SegmentedControlIosPillToggleProps = {
  legend?: string;
  options?: string[];
  duration?: number;
  easing?: string;
  pillColor?: string;
};

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

export default function SegmentedControlIosPillToggle({
  legend = "Status filter",
  options = ["All", "Active", "Done"],
  duration = 220,
  easing = "cubic-bezier(.2,1.4,.4,1)",
  pillColor = "#2f6df6",
}: SegmentedControlIosPillToggleProps) {
  const [index, setIndex] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--pill": pillColor };

  return (
    <fieldset className={styles.seg} style={vars}>
      <legend className={styles.srOnly}>{legend}</legend>
      <div className={styles.track}>
        <span
          className={styles.pill}
          style={{ transform: `translateX(${index * 100}%)`, width: `calc(100% / ${options.length})` }}
          aria-hidden="true"
        />
        {options.map((label, i) => (
          <label key={label} className={styles.tab} data-active={index === i}>
            <input
              type="radio"
              name="seg"
              className={styles.srInput}
              checked={index === i}
              onChange={() => setIndex(i)}
            />
            {label}
          </label>
        ))}
      </div>
    </fieldset>
  );
}