07Viền vòng đôi

<main class="stage">
  <button class="btn is-demo" type="button">Đăng ký</button>
</main>

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

$duration: $dur-base;                                   // 실제 호버 시 바깥 링이 퍼지는 시간
$easing: $ease-out;
$color: $subject-cream;                                 // 링 색

@include stage($stage-orange);
.stage { padding: clamp(6px, 2.4vw, 16px); }

.btn {
  position: relative;
  border: 0;
  border-radius: $r-pill;
  padding: 14px 30px;
  font-weight: 700; font-size: clamp(13px, 3.6vw, 15px); line-height: 1; font-family: inherit;
  color: $stage-ink;
  background: $color;
  cursor: pointer;
  box-shadow: 0 0 0 3px rgba($color, .9);               // 안쪽 고정 링
}
.btn::after {                                            // 바깥 링 — 평소엔 숨어 있다
  content: "";
  position: absolute;
  inset: -3px;
  border-radius: inherit;
  border: 2px solid $color;
  opacity: 0;
  transform: scale(1);
  transition: transform $duration $easing, opacity $duration $easing;
}
.btn:hover::after, .btn:focus-visible::after { opacity: 1; transform: scale(1.3); }

.btn.is-demo::after { animation: ring-pulse $dur-loop $easing infinite; }
@keyframes ring-pulse {
  0%, 15%  { transform: scale(1); opacity: .9; }
  70%      { transform: scale(1.35); opacity: 0; }
  100%     { transform: scale(1.35); opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .btn::after { transition: none; }
  .btn.is-demo::after { animation: none; opacity: 0; }
}

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);
}

.stage {
  padding: clamp(6px, 2.4vw, 16px);
}

.btn {
  position: relative;
  border: 0;
  border-radius: 999px;
  padding: 14px 30px;
  font-weight: 700;
  font-size: clamp(13px, 3.6vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  background: #fff7e6;
  cursor: pointer;
  box-shadow: 0 0 0 3px rgba(255, 247, 230, 0.9);
}

.btn::after {
  content: "";
  position: absolute;
  inset: -3px;
  border-radius: inherit;
  border: 2px solid #fff7e6;
  opacity: 0;
  transform: scale(1);
  transition: transform 300ms ease-out, opacity 300ms ease-out;
}

.btn:hover::after, .btn:focus-visible::after {
  opacity: 1;
  transform: scale(1.3);
}

.btn.is-demo::after {
  animation: ring-pulse 2s ease-out infinite;
}

@keyframes ring-pulse {
  0%, 15% {
    transform: scale(1);
    opacity: 0.9;
  }
  70% {
    transform: scale(1.35);
    opacity: 0;
  }
  100% {
    transform: scale(1.35);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .btn::after {
    transition: none;
  }
  .btn.is-demo::after {
    animation: none;
    opacity: 0;
  }
}

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

export type DoubleRingButtonProps = {
  label: string;
  /** 실제 호버 시 바깥 링이 퍼지는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
  /** 링 색 */
  color?: string;
};

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

export default function DoubleRingButton({
  label,
  duration = 300,
  easing = "ease-out",
  color = "#fff7e6",
}: DoubleRingButtonProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <button className={styles.btn} style={vars} type="button">
      {label}
    </button>
  );
}