07Ring grows on hover

<main class="stage">
  <a class="link link--a" href="#">Features</a>
  <a class="link link--b" href="#">Pricing</a>
  <div class="cursor-pos is-demo" aria-hidden="true"><div class="ring"></div></div>
</main>

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

$duration: $dur-loop;                                 // 링이 두 링크를 도는 한 바퀴
$easing: $ease-spring;
$color: $subject-cream;                                // 링 색

@include stage($stage-orange);

.stage { position: relative; overflow: hidden; cursor: none; }

.link {
  position: absolute;
  padding: clamp(8px, 2.4vw, 12px) clamp(16px, 4.4vw, 22px);
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .14);
  color: $subject-ink;                                   // AA: 주황 면(흰 14% 겹침 #d2ada4) 위 5.96:1
  font-weight: 700; font-size: clamp(12px, 3.2vw, 15px); line-height: 1; font-family: inherit;
  text-decoration: none;
}
.link--a { top: 22%; left: 14%; }
.link--b { bottom: 22%; right: 14%; }

.cursor-pos {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;

  &.is-demo { animation: cursor-path $duration $easing infinite; }
}

.ring {
  width: 30px;
  height: 30px;
  margin: -15px 0 0 -15px;
  border: 2px solid $color;
  border-radius: 50%;
  transition: transform 180ms $easing;
}

// 실제 조작: 링크 위에 실제 포인터가 있으면 :has() 로 링을 키운다
.stage:has(.link:hover) .ring { transform: scale(1.6); }

.cursor-pos.is-demo .ring { animation: ring-grow $duration $easing infinite; }

@keyframes cursor-path {
  0%   { transform: translate(90px, 60px); }
  40%  { transform: translate(90px, 60px); }            // link--a 위
  50%  { transform: translate(300px, 210px); }
  90%  { transform: translate(300px, 210px); }           // link--b 위
  100% { transform: translate(90px, 60px); }
}

@keyframes ring-grow {
  0%, 100% { transform: scale(1); }
  20%, 40% { transform: scale(1.6); }
  50%, 70% { transform: scale(1.6); }
  80%      { transform: scale(1); }
}

@media (pointer: coarse) {
  .cursor-pos { display: none; }
  .stage { cursor: auto; }
}

@media (prefers-reduced-motion: reduce) {
  .cursor-pos.is-demo { animation: none; transform: translate(90px, 60px); }
  .cursor-pos.is-demo .ring { animation: none; }
}

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 {
  position: relative;
  overflow: hidden;
  cursor: none;
}

.link {
  position: absolute;
  padding: clamp(8px, 2.4vw, 12px) clamp(16px, 4.4vw, 22px);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.14);
  color: #17141a;
  font-weight: 700;
  font-size: clamp(12px, 3.2vw, 15px);
  line-height: 1;
  font-family: inherit;
  text-decoration: none;
}

.link--a {
  top: 22%;
  left: 14%;
}

.link--b {
  bottom: 22%;
  right: 14%;
}

.cursor-pos {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
}
.cursor-pos.is-demo {
  animation: cursor-path 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.ring {
  width: 30px;
  height: 30px;
  margin: -15px 0 0 -15px;
  border: 2px solid #fff7e6;
  border-radius: 50%;
  transition: transform 180ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.stage:has(.link:hover) .ring {
  transform: scale(1.6);
}

.cursor-pos.is-demo .ring {
  animation: ring-grow 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes cursor-path {
  0% {
    transform: translate(90px, 60px);
  }
  40% {
    transform: translate(90px, 60px);
  }
  50% {
    transform: translate(300px, 210px);
  }
  90% {
    transform: translate(300px, 210px);
  }
  100% {
    transform: translate(90px, 60px);
  }
}
@keyframes ring-grow {
  0%, 100% {
    transform: scale(1);
  }
  20%, 40% {
    transform: scale(1.6);
  }
  50%, 70% {
    transform: scale(1.6);
  }
  80% {
    transform: scale(1);
  }
}
@media (pointer: coarse) {
  .cursor-pos {
    display: none;
  }
  .stage {
    cursor: auto;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cursor-pos.is-demo {
    animation: none;
    transform: translate(90px, 60px);
  }
  .cursor-pos.is-demo .ring {
    animation: none;
  }
}

// 실제 포인터가 움직이면 링이 좌표를 따라가고, 링크 위에서는 :has() 로 링이 커진다.
if (matchMedia('(pointer: fine)').matches) {
  var stage = document.querySelector('.stage'), pos = document.querySelector('.cursor-pos');
  stage.addEventListener('pointermove', function (e) {
    pos.classList.remove('is-demo');
    var r = stage.getBoundingClientRect();
    pos.style.transform = 'translate(' + (e.clientX - r.left) + 'px,' + (e.clientY - r.top) + 'px)';
  });
}

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

export type HoverGrowRingProps = {
  links?: string[];
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function HoverGrowRing({
  links = ["기능", "가격"],
  duration = 2000,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#fff7e6",
}: HoverGrowRingProps) {
  const [demo, setDemo] = useState(true);
  const [pos, setPos] = useState({ x: 90, y: 60 });
  const [grow, setGrow] = useState(false);

  const move = (e: PointerEvent<HTMLDivElement>) => {
    setDemo(false);
    const r = e.currentTarget.getBoundingClientRect();
    setPos({ x: e.clientX - r.left, y: e.clientY - r.top });
    setGrow((e.target as HTMLElement).closest("a") !== null);
  };

  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.stage} style={vars} onPointerMove={move}>
      <a className={`${styles.link} ${styles.linkA}`} href="#">{links[0]}</a>
      <a className={`${styles.link} ${styles.linkB}`} href="#">{links[1]}</a>
      <div
        className={demo ? `${styles.cursorPos} ${styles.isDemo}` : styles.cursorPos}
        style={demo ? undefined : { transform: `translate(${pos.x}px,${pos.y}px)` }}
        aria-hidden="true"
      >
        <div className={grow ? `${styles.ring} ${styles.ringGrow}` : styles.ring} />
      </div>
    </div>
  );
}