03Field validation glow ring

<main class="stage">
  <div class="fv3 is-demo">
    <span class="fv3__field">
      <input class="fv3__input" type="text" value="[email protected]" readonly>
      <span class="fv3__glow" aria-hidden="true"></span>
    </span>
  </div>
</main>

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

// 검증을 통과한 필드 뒤에 글로우 링이 떠오른다: box-shadow 레이어의 opacity + scale 만 움직인다
$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-mint;

@include stage($stage-orange);

.fv3 { width: min(240px, 86vw); }
.fv3__field { position: relative; display: block; }
.fv3__glow {
  position: absolute; inset: -6px; border-radius: $r-control;
  box-shadow: 0 0 0 4px rgba(76, 212, 166, .55);
  opacity: 0; transform: scale(.94); pointer-events: none;
}
.fv3__input {
  position: relative; box-sizing: border-box; width: 100%;
  padding: $sp-2 $sp-3; border-radius: $r-sm;
  border: 2px solid $color; background: $subject-cream;
  color: $subject-ink; font-weight: 400; font-size: 14px; line-height: 1; font-family: inherit;
}

// 한 겹(감쇠 진동): 45% 피크 뒤 단순 소멸 대신 52%·58%·64% 에 점점 약해지는 2·3차 파동이 잦아들며 사라진다
@keyframes fv3-glow {
  0%, 15% { opacity: 0; transform: scale(.94); }
  45% { opacity: 1; transform: scale(1.04); }
  48.5% { opacity: .35; transform: scale(.985); }
  52% { opacity: .62; transform: scale(1.015); }
  55% { opacity: .18; transform: scale(.985); }
  58% { opacity: .34; transform: scale(1.008); }
  61% { opacity: .08; transform: scale(.992); }
  64% { opacity: .16; transform: scale(1.004); }
  68% { opacity: 0; transform: scale(.94); }
  75%, 100% { opacity: 0; transform: scale(.94); }
}
.fv3.is-demo .fv3__glow { animation: fv3-glow $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .fv3.is-demo .fv3__glow { animation: none !important; opacity: .6; transform: scale(1); }
}

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);
}

.fv3 {
  width: min(240px, 86vw);
}

.fv3__field {
  position: relative;
  display: block;
}

.fv3__glow {
  position: absolute;
  inset: -6px;
  border-radius: 12px;
  box-shadow: 0 0 0 4px rgba(76, 212, 166, 0.55);
  opacity: 0;
  transform: scale(0.94);
  pointer-events: none;
}

.fv3__input {
  position: relative;
  box-sizing: border-box;
  width: 100%;
  padding: 8px 12px;
  border-radius: 8px;
  border: 2px solid #4cd4a6;
  background: #fff7e6;
  color: #17141a;
  font-weight: 400;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}

@keyframes fv3-glow {
  0%, 15% {
    opacity: 0;
    transform: scale(0.94);
  }
  45% {
    opacity: 1;
    transform: scale(1.04);
  }
  48.5% {
    opacity: 0.35;
    transform: scale(0.985);
  }
  52% {
    opacity: 0.62;
    transform: scale(1.015);
  }
  55% {
    opacity: 0.18;
    transform: scale(0.985);
  }
  58% {
    opacity: 0.34;
    transform: scale(1.008);
  }
  61% {
    opacity: 0.08;
    transform: scale(0.992);
  }
  64% {
    opacity: 0.16;
    transform: scale(1.004);
  }
  68% {
    opacity: 0;
    transform: scale(0.94);
  }
  75%, 100% {
    opacity: 0;
    transform: scale(0.94);
  }
}
.fv3.is-demo .fv3__glow {
  animation: fv3-glow 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .fv3.is-demo .fv3__glow {
    animation: none !important;
    opacity: 0.6;
    transform: scale(1);
  }
}

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

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

export default function FieldGlowRing({ duration = 2000, easing = "cubic-bezier(.2,.8,.2,1)", color = "#4cd4a6" }: FieldGlowRingProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={styles.fv3} style={vars}>
      <span className={styles.field}>
        <input className={styles.input} type="text" defaultValue="[email protected]" readOnly />
        <span className={styles.glow} aria-hidden="true" />
      </span>
    </div>
  );
}