04Search box expand

<main class="stage">
  <label class="se is-demo" for="se-input">
    <svg class="se__icon" viewBox="0 0 24 24" aria-hidden="true"><circle cx="11" cy="11" r="6.5"/><line x1="20" y1="20" x2="15.7" y2="15.7"/></svg>
    <input id="se-input" class="se__input" type="search" placeholder="Type to search" aria-label="Search">
    <span class="se__bloom" aria-hidden="true"></span>
  </label>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;                  // 폭이 넓어지는 시간
$easing: cubic-bezier(.3, 1.4, .4, 1); // 스프링 오버슛 — 폭이 목표 240px 을 지나 살짝 뻗었다가 돌아온다
$color: $subject-ink;                  // 포커스 시 테두리·아이콘 색

@include stage($stage-paper);

.se {
  display: inline-flex;
  align-items: center;
  gap: $sp-2;
  border-radius: $r-pill;
  border: 2px solid rgba($stage-ink, .25);
  padding: $sp-3 $sp-4;
  cursor: text;
  background: $subject-cream;
  width: 148px;
  position: relative;
  transition: width $duration $easing, border-color $duration $easing;
}
// 실사용: 입력에 포커스가 가면(:focus-within) 폭이 넓어진다
.se:focus-within { width: 240px; border-color: $color; }

// 포커스 순간 필 중심에서 번지는 radial 글로우 확산 한 겹
.se__bloom {
  position: absolute;
  inset: -8px;
  border-radius: $r-pill;
  background: radial-gradient(ellipse at 50% 50%, rgba($color, .18) 0%, rgba($color, 0) 70%);
  opacity: 0;
  pointer-events: none;
}
.se:focus-within .se__bloom { animation: se-bloom $dur-base $ease-out; }

@keyframes se-bloom {
  0%   { opacity: 0; transform: scale(.7); }
  40%  { opacity: 1; transform: scale(1); }
  100% { opacity: 0; transform: scale(1.2); }
}

.se__icon {
  width: 18px; height: 18px;
  flex: none;
  fill: none;
  stroke: $color;
  stroke-width: 2;
  stroke-linecap: round;
}
.se__input {
  border: 0;
  outline: 0;
  background: transparent;
  width: 100%;
  font-weight: 500;
  font-size: clamp(13px, 3.8vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: $stage-ink;
}

@media (prefers-reduced-motion: reduce) {
  .se { transition: none; }
  .se:focus-within .se__bloom { animation: none; }
}

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

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

.se {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border-radius: 999px;
  border: 2px solid rgba(23, 20, 26, 0.25);
  padding: 12px 16px;
  cursor: text;
  background: #fff7e6;
  width: 148px;
  position: relative;
  transition: width 300ms cubic-bezier(0.3, 1.4, 0.4, 1), border-color 300ms cubic-bezier(0.3, 1.4, 0.4, 1);
}

.se:focus-within {
  width: 240px;
  border-color: #17141a;
}

.se__bloom {
  position: absolute;
  inset: -8px;
  border-radius: 999px;
  background: radial-gradient(ellipse at 50% 50%, rgba(23, 20, 26, 0.18) 0%, rgba(23, 20, 26, 0) 70%);
  opacity: 0;
  pointer-events: none;
}

.se:focus-within .se__bloom {
  animation: se-bloom 300ms ease-out;
}

@keyframes se-bloom {
  0% {
    opacity: 0;
    transform: scale(0.7);
  }
  40% {
    opacity: 1;
    transform: scale(1);
  }
  100% {
    opacity: 0;
    transform: scale(1.2);
  }
}
.se__icon {
  width: 18px;
  height: 18px;
  flex: none;
  fill: none;
  stroke: #17141a;
  stroke-width: 2;
  stroke-linecap: round;
}

.se__input {
  border: 0;
  outline: 0;
  background: transparent;
  width: 100%;
  font-weight: 500;
  font-size: clamp(13px, 3.8vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}

@media (prefers-reduced-motion: reduce) {
  .se {
    transition: none;
  }
  .se:focus-within .se__bloom {
    animation: none;
  }
}

// .is-demo 자동 재생: 진짜 focus 를 오가며 :focus-within 을 그대로 탄다 (3줄)
var el = document.querySelector('.is-demo .se__input');
var t = function () { document.activeElement === el ? el.blur() : el.focus({ preventScroll: true }); };  // preventScroll — iframe 안 포커스가 홈 그리드의 부모 스크롤을 끌어당기지 않게 (사용자 2026-09-10 실측)
t(); setInterval(t, 450);

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

export type SearchExpandProps = {
  placeholder?: string;
  ariaLabel?: string;
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function SearchExpand({
  placeholder = "Type to search",
  ariaLabel = "Search",
  duration = 300,
  easing = "cubic-bezier(.3,1.4,.4,1)",
  color = "#17141a",
}: SearchExpandProps) {
  const [value, setValue] = useState("");
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <label className={styles.se} style={vars}>
      <svg className={styles.icon} viewBox="0 0 24 24" aria-hidden="true">
        <circle cx="11" cy="11" r="6.5" />
        <line x1="20" y1="20" x2="15.7" y2="15.7" />
      </svg>
      <input
        className={styles.input}
        type="search"
        placeholder={placeholder}
        aria-label={ariaLabel}
        value={value}
        onChange={(e: ChangeEvent<HTMLInputElement>) => setValue(e.target.value)}
      />
      <span className={styles.bloom} aria-hidden="true" />
    </label>
  );
}