09스르륵 매끄러운(ぬるっと)

<main class="stage">
  <a class="link o-nuru is-demo" href="#">
    자세히 보기
    <span class="link__arrow" aria-hidden="true">→</span>
  </a>
  <span class="tag">스르륵</span>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: 700ms;
$easing: cubic-bezier(.16, 1, .3, 1);   // ease-out-expo 근사 — 매끄럽게 감속한다
$color: $subject-blue;

// ── 데모 무대 ───────────────────────────────
@include stage($stage-ink);
.stage { position: relative; }

.link {
  display: inline-flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-3 $sp-2;
  color: $subject-cream;
  text-decoration: none;
  font-weight: 700;
  font-size: clamp(16px, 4.5vw, 19px);
  line-height: 1;
  font-family: inherit;
  border-bottom: 2px solid rgba(255, 247, 230, .3);
}
.link__arrow {
  display: inline-block;
  color: $color;
  font-size: 22px;
}
.tag {
  position: absolute;
  top: $sp-4;
  right: $sp-4;
  padding: $sp-1 $sp-3;
  border-radius: $r-sm;
  background: rgba(255, 255, 255, .12);
  color: $subject-cream;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: .04em;
}

// ── 실제 쓰임: 마우스를 올리면(또는 포커스) 화살표가 미끄러지듯 이동한다 ─────
.link.o-nuru:hover .link__arrow,
.link.o-nuru:focus-visible .link__arrow { animation: o-nuru $duration $easing 1; }

// ── 데모: 2초마다 스스로 미끄러진다 ─────
.link.o-nuru.is-demo .link__arrow { animation: o-nuru-loop $dur-loop $easing infinite; }

@keyframes o-nuru {
  0%   { transform: translateX(0)   scale(1); }
  100% { transform: translateX(28px) scale(1.15); }
}
@keyframes o-nuru-loop {
  0%, 40%  { transform: translateX(0)    scale(1); }
  78%      { transform: translateX(28px) scale(1.15); }
  100%     { transform: translateX(0)    scale(1); }
}

// ── 접근성 ──────────────────────────────────────────
@media (prefers-reduced-motion: reduce) {
  .link.o-nuru:hover .link__arrow, .link.o-nuru:focus-visible .link__arrow,
  .link.o-nuru.is-demo .link__arrow { animation: none; }
}

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);
}

.stage {
  position: relative;
}

.link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 8px;
  color: #fff7e6;
  text-decoration: none;
  font-weight: 700;
  font-size: clamp(16px, 4.5vw, 19px);
  line-height: 1;
  font-family: inherit;
  border-bottom: 2px solid rgba(255, 247, 230, 0.3);
}

.link__arrow {
  display: inline-block;
  color: #2f6df6;
  font-size: 22px;
}

.tag {
  position: absolute;
  top: 16px;
  right: 16px;
  padding: 4px 12px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.12);
  color: #fff7e6;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.04em;
}

.link.o-nuru:hover .link__arrow,
.link.o-nuru:focus-visible .link__arrow {
  animation: o-nuru 700ms cubic-bezier(0.16, 1, 0.3, 1) 1;
}

.link.o-nuru.is-demo .link__arrow {
  animation: o-nuru-loop 2s cubic-bezier(0.16, 1, 0.3, 1) infinite;
}

@keyframes o-nuru {
  0% {
    transform: translateX(0) scale(1);
  }
  100% {
    transform: translateX(28px) scale(1.15);
  }
}
@keyframes o-nuru-loop {
  0%, 40% {
    transform: translateX(0) scale(1);
  }
  78% {
    transform: translateX(28px) scale(1.15);
  }
  100% {
    transform: translateX(0) scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .link.o-nuru:hover .link__arrow, .link.o-nuru:focus-visible .link__arrow,
  .link.o-nuru.is-demo .link__arrow {
    animation: none;
  }
}

import type { CSSProperties, ReactNode } from "react";
import styles from "./SmoothLink.module.scss";

export type SmoothLinkProps = {
  children: ReactNode;
  href?: string;
  /** 미끄러지는 데 걸리는 시간 (기본 700ms) */
  duration?: number;
  /** CSS easing (기본 ease-out-expo 근사) */
  easing?: string;
  color?: string;
};

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

export default function SmoothLink({
  children,
  href = "#",
  duration = 700,
  easing = "cubic-bezier(.16,1,.3,1)",
  color = "#2f6df6",
}: SmoothLinkProps) {
  const vars: Vars = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
  };
  return (
    <a className={styles.link} href={href} style={vars}>
      {children}
      <span className={styles.arrow} aria-hidden="true">
        →
      </span>
    </a>
  );
}