03八方向の値が重なり輪郭線になる文字

<main class="stage">
<div class="ol is-demo" id="ol">
  <p class="ol__badge"><span class="ol__badgeLabel">輪郭の太さ</span> <span class="ol__badgeValue" id="olValue">0.5px</span></p>
  <h1 class="ol__word" id="olWord">輪郭</h1>
</div>
</main>

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

// 핵심: 값 d 하나를 여덟 방향(상하좌우+대각선)에 같은 거리만큼 겹쳐, 글자 채움 없이도
// 둘레에 윤곽선만 남는다. d 가 커질수록 윤곽선이 두꺼워진다.

$duration: $dur-loop;
$easing: linear;
$color: $stage-orange;

@include stage($stage-orange);

.ol {
  display: grid;
  gap: $sp-4;
  justify-items: center;
  text-align: center;
}

.ol__badge {
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(23, 20, 26, .12);
  color: $subject-ink;
  font-weight: 700;
  font-size: 11px;
  font-variant-numeric: tabular-nums;
}

.ol__word {
  margin: 0;
  font-weight: 800;
  font-size: clamp(72px, 24vw, 140px);
  line-height: 1;
  white-space: nowrap;
  color: $color;
  will-change: text-shadow;
}

@media (max-width: 340px) {
  .ol__word { font-size: clamp(52px, 26vw, 92px); }
}

@media (prefers-reduced-motion: reduce) {
  .ol__word { transition: 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);
}

.ol {
  display: grid;
  gap: 16px;
  justify-items: center;
  text-align: center;
}

.ol__badge {
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.12);
  color: #17141a;
  font-weight: 700;
  font-size: 11px;
  font-variant-numeric: tabular-nums;
}

.ol__word {
  margin: 0;
  font-weight: 800;
  font-size: clamp(72px, 24vw, 140px);
  line-height: 1;
  white-space: nowrap;
  color: #ff4d1f;
  will-change: text-shadow;
}

@media (max-width: 340px) {
  .ol__word {
    font-size: clamp(52px, 26vw, 92px);
  }
}
@media (prefers-reduced-motion: reduce) {
  .ol__word {
    transition: none;
  }
}

(function () {
  var OUTLINE_MAX_PX = 15;
  var PERIOD_MS = 1000;
  var DIRS = [
    [1, 0], [-1, 0], [0, 1], [0, -1],
    [0.7071, 0.7071], [-0.7071, 0.7071], [0.7071, -0.7071], [-0.7071, -0.7071]
  ];

  var word = document.getElementById('olWord');
  var value = document.getElementById('olValue');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  // 값(d) 하나를 여덟 방향에 같은 거리만큼 겹쳐 채움 없이도 윤곽선만 남긴다
  function buildOutlineShadow(d) {
    var parts = [];
    for (var i = 0; i < DIRS.length; i++) {
      var x = (DIRS[i][0] * d).toFixed(2);
      var y = (DIRS[i][1] * d).toFixed(2);
      parts.push(x + 'px ' + y + 'px 0 rgba(23,20,26,.92)');
    }
    return parts.join(', ');
  }

  function renderOutline(d) {
    word.style.textShadow = buildOutlineShadow(d);
    value.textContent = d.toFixed(1) + 'px';
  }

  var startTime = null;
  function loop(now) {
    if (startTime === null) startTime = now;
    var t = (now - startTime) % PERIOD_MS;
    var phase = (Math.sin((t / PERIOD_MS) * Math.PI * 2 - Math.PI / 2) + 1) / 2;
    renderOutline(0.4 + (OUTLINE_MAX_PX - 0.4) * phase);
    requestAnimationFrame(loop);
  }

  if (reduce) {
    renderOutline(OUTLINE_MAX_PX);
  } else {
    requestAnimationFrame(loop);
  }
})();

// TextShadowStrokeOutlineMulti — vanilla 판(run/412/demo/03-text-shadow-stroke-outline-multi/index.html) 의 React 포트.
// 값 d 하나를 여덟 방향(상하좌우+대각선)에 같은 거리만큼 겹쳐, 글자 채움 없이도
// 둘레에 윤곽선만 남는다. d 가 커질수록 윤곽선이 두꺼워진다.
import { useEffect, useRef, useState } from "react";
import styles from "./TextShadowStrokeOutlineMulti.module.scss";

type Box<T> = { current: T };

const OUTLINE_MAX_PX = 15;
const PERIOD_MS = 1000;
const DIRS: [number, number][] = [
  [1, 0], [-1, 0], [0, 1], [0, -1],
  [0.7071, 0.7071], [-0.7071, 0.7071], [0.7071, -0.7071], [-0.7071, -0.7071]
];

function buildOutlineShadow(d: number): string {
  const parts: string[] = [];
  for (let i = 0; i < DIRS.length; i++) {
    const x = (DIRS[i][0] * d).toFixed(2);
    const y = (DIRS[i][1] * d).toFixed(2);
    parts.push(x + "px " + y + "px 0 rgba(23,20,26,.92)");
  }
  return parts.join(", ");
}

export default function TextShadowStrokeOutlineMulti() {
  const wordRef = useRef<HTMLHeadingElement | null>(null);
  const valueRef = useRef<HTMLSpanElement | null>(null);
  const t0Ref = useRef<number>(0) as Box<number>;
  const frameRef = useRef<number>(0) as Box<number>;
  const [demo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(d: number): void {
    const word = wordRef.current;
    const value = valueRef.current;
    if (!word || !value) return;
    word.style.textShadow = buildOutlineShadow(d);
    value.textContent = d.toFixed(1) + "px";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(OUTLINE_MAX_PX);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) % PERIOD_MS;
      const phase = (Math.sin((t / PERIOD_MS) * Math.PI * 2 - Math.PI / 2) + 1) / 2;
      render(0.4 + (OUTLINE_MAX_PX - 0.4) * phase);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  const cls = [styles.ol, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.badge}><span>윤곽 두께</span> <span ref={valueRef}>0.5px</span></p>
        <h1 className={styles.word} ref={wordRef}>윤곽</h1>
      </div>
    </main>
  );
}