05エラーフィールドの呼吸リング

<main class="stage">
  <div class="fv5 is-demo">
    <span class="fv5__field">
      <input class="fv5__input" type="text" value="01021" readonly>
      <span class="fv5__ring" aria-hidden="true"></span>
    </span>
    <p class="fv5__msg">数字を4桁以上入力してください</p>
  </div>
</main>

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

// 052편(shake-error) 은 흔들림이다. 여기서는 흔들지 않고, 필드 둘레의 글로우 링이 opacity + scale 로 천천히 숨쉬듯 반복하며 오류를 알린다
$duration: $dur-loop;
$easing: $ease-out;
$color: $error;

@include stage($stage-ink);

.fv5 { width: min(240px, 86vw); display: flex; flex-direction: column; gap: $sp-2; }
.fv5__field { position: relative; display: block; }
.fv5__ring {
  position: absolute; inset: -5px; border-radius: $r-control;
  box-shadow: 0 0 0 3px $error-soft; opacity: 0; transform: scale(.97); pointer-events: none;
}
.fv5__input {
  position: relative; box-sizing: border-box; width: 100%;
  padding: $sp-2 $sp-3; border-radius: $r-sm;
  border: 2px solid $color; background: rgba(255, 255, 255, .06);
  color: $subject-cream; font-weight: 400; font-size: 14px; line-height: 1; font-family: inherit;
}
.fv5__msg { margin: 0; color: $color; font-weight: 500; font-size: 11px; line-height: 1.3; font-family: inherit; }

// 한 겹(감쇠 진동): 50% 피크 뒤 단조 소멸 대신 62%·74%·86% 에 점점 약해지는 2·3차 파동 — 필드는 절대 움직이지 않는다(052 흔들림과의 차별화 유지)
@keyframes fv5-breathe {
  0%, 100% { opacity: 0; transform: scale(.97); }
  50% { opacity: 1; transform: scale(1.03); }
  54% { opacity: .45; transform: scale(.99); }
  58% { opacity: .72; transform: scale(1.022); }
  62% { opacity: .3; transform: scale(.992); }
  66% { opacity: .48; transform: scale(1.015); }
  70% { opacity: .18; transform: scale(.995); }
  74% { opacity: .28; transform: scale(1.009); }
  78% { opacity: .1; transform: scale(.997); }
  82% { opacity: .15; transform: scale(1.005); }
  86% { opacity: .05; transform: scale(.999); }
  92% { opacity: 0; transform: scale(.97); }
}
.fv5.is-demo .fv5__ring { animation: fv5-breathe $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .fv5.is-demo .fv5__ring { animation: none !important; opacity: .7; 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: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.fv5 {
  width: min(240px, 86vw);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.fv5__field {
  position: relative;
  display: block;
}

.fv5__ring {
  position: absolute;
  inset: -5px;
  border-radius: 12px;
  box-shadow: 0 0 0 3px #ffe0d8;
  opacity: 0;
  transform: scale(0.97);
  pointer-events: none;
}

.fv5__input {
  position: relative;
  box-sizing: border-box;
  width: 100%;
  padding: 8px 12px;
  border-radius: 8px;
  border: 2px solid #c2361a;
  background: rgba(255, 255, 255, 0.06);
  color: #fff7e6;
  font-weight: 400;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}

.fv5__msg {
  margin: 0;
  color: #c2361a;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
  font-family: inherit;
}

@keyframes fv5-breathe {
  0%, 100% {
    opacity: 0;
    transform: scale(0.97);
  }
  50% {
    opacity: 1;
    transform: scale(1.03);
  }
  54% {
    opacity: 0.45;
    transform: scale(0.99);
  }
  58% {
    opacity: 0.72;
    transform: scale(1.022);
  }
  62% {
    opacity: 0.3;
    transform: scale(0.992);
  }
  66% {
    opacity: 0.48;
    transform: scale(1.015);
  }
  70% {
    opacity: 0.18;
    transform: scale(0.995);
  }
  74% {
    opacity: 0.28;
    transform: scale(1.009);
  }
  78% {
    opacity: 0.1;
    transform: scale(0.997);
  }
  82% {
    opacity: 0.15;
    transform: scale(1.005);
  }
  86% {
    opacity: 0.05;
    transform: scale(0.999);
  }
  92% {
    opacity: 0;
    transform: scale(0.97);
  }
}
.fv5.is-demo .fv5__ring {
  animation: fv5-breathe 2s ease-out infinite;
}

@media (prefers-reduced-motion: reduce) {
  .fv5.is-demo .fv5__ring {
    animation: none !important;
    opacity: 0.7;
    transform: scale(1);
  }
}

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

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

export default function ErrorBorderPulse({ duration = 2000, easing = "ease-out", color = "#c2361a" }: ErrorBorderPulseProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={styles.fv5} style={vars}>
      <span className={styles.field}>
        <input className={styles.input} type="text" defaultValue="01021" readOnly />
        <span className={styles.ring} aria-hidden="true" />
      </span>
      <p className={styles.msg}>숫자만 4자리 이상 입력해 주세요</p>
    </div>
  );
}