02CRT scanlines and curved vignette

<main class="stage">
<figure class="crt">
  <div class="crt__bezel">
    <div class="crt__screen">
      <div class="crt__content">
        <p class="crt__title">Retro OS</p>
        <p class="crt__sub">CRT monitor effect — CSS only</p>
      </div>
      <span class="crt__band" aria-hidden="true"></span>
      <span class="crt__lines" aria-hidden="true"></span>
      <span class="crt__vig" aria-hidden="true"></span>
    </div>
  </div>
  <figcaption class="crt__cap">One stripe tile and an elliptical vignette fake a CRT tube</figcaption>
</figure>
</main>

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

// CRT 스캔라인과 곡면 비네트 — 가로 줄무늬를 타일 하나(4px, 그 안 줄 위치 0 부터 2px)로 정의해
// background-size 로 반복시키고, radial-gradient 타원으로 가장자리로 갈수록 어두워지는 유리를 얹는다.
// 밝은 띠 하나가 translateY 로 위에서 아래로 흐른다. 화면 안쪽 바탕은 비토큰 배경 픽셀(짙은 남색)이다.

$duration: $dur-loop;
$easing: $ease-out;
$color: $subject-cream;
$mono: ui-monospace, SFMono-Regular, "SF Mono", Consolas, "Liberation Mono", monospace;
$glass: #0d1220;   // 비토큰 배경 픽셀 — 브라운관 형광면의 짙은 남색 바탕(주변 토큰으로는 없는 색)

@include stage($stage-yellow);

.crt {
  display: flex; flex-direction: column; gap: $sp-2;
  width: min(100%, 340px); margin: 0;
}

// ── 모니터 껍데기
.crt__bezel {
  box-sizing: border-box; padding: $sp-3;
  background: $subject-ink; border-radius: $r-card;
  box-shadow: $shadow-raised;
}

// ── 유리면 — 안의 도형은 전부 이 상자에 absolute 로 겹친다. 밖으로 나가면 잘린다
.crt__screen {
  position: relative; overflow: hidden;
  display: grid; place-items: center;
  height: clamp(112px, 58vh, 196px);
  background: $glass;
  border-radius: $r-sm;
}

.crt__content {
  position: relative; z-index: 1;
  display: grid; gap: $sp-1; justify-items: center;
  padding: $sp-2; text-align: center;
}
.crt__title {
  margin: 0; color: $color;
  font-family: $mono; font-weight: 700;
  font-size: clamp(16px, 4.2vh, 22px); line-height: 1.2;
  letter-spacing: .08em;
  text-shadow: 0 0 12px rgba($subject-cream, .35);   // 형광체 빛 번짐
}
.crt__sub {
  margin: 0; color: rgba($subject-cream, .82);
  font-family: $mono; font-weight: 500;
  font-size: clamp(10px, 2.6vh, 12px); line-height: 1.4;
  letter-spacing: .04em;
}

// ── 위에서 아래로 흐르는 밝은 띠 — transform 만 움직인다
.crt__band {
  position: absolute; left: 0; right: 0; top: 0; z-index: 2;
  height: 30%; pointer-events: none;
  background: linear-gradient(to bottom,
    transparent,
    rgba($subject-cream, .08) 28%,
    rgba($subject-cream, .14) 50%,
    rgba($subject-cream, .08) 72%,
    transparent);
  animation-name: crtBand;
  animation-duration: $duration;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

// ── 스캔라인 — 타일(4px)을 background-size 로 정의하고 그 안에 줄 위치를 둔다
.crt__lines {
  position: absolute; inset: 0; z-index: 3; pointer-events: none;
  background-image: repeating-linear-gradient(to bottom,
    rgba($subject-ink, .38) 0 2px,
    transparent 2px 4px);
  background-size: 100% 4px;
}

// ── 곡면 비네트 — 타원으로 가장자리가 감아 들어가는 유리
.crt__vig {
  position: absolute; inset: 0; z-index: 4; pointer-events: none;
  border-radius: inherit;
  background: radial-gradient(ellipse 130% 105% at 50% 46%,
    transparent 40%,
    rgba($subject-ink, .18) 64%,
    rgba($subject-ink, .55) 100%);
}

.crt__cap {
  margin: 0; color: $subject-ink;
  font-weight: 500; font-size: 11px; line-height: 1.4;
  text-align: center;
}

// 띠는 화면 높이의 넉 배 남짓을 지나가므로 시작과 끝이 모두 화면 밖 — 루프 이음새가 보이지 않는다
@keyframes crtBand {
  0% { transform: translateY(-110%); }
  100% { transform: translateY(500%); }
}

// ── 좁은 화면: 껍데기와 캡션을 줄인다(화면 높이는 vh 기준이라 함께 줄어든다)
@media (max-width: 340px) {
  .crt { gap: $sp-1; }
  .crt__bezel { padding: $sp-2; }
  .crt__cap { font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  .crt__band { animation: none !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.crt {
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: min(100%, 340px);
  margin: 0;
}

.crt__bezel {
  box-sizing: border-box;
  padding: 12px;
  background: #17141a;
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.crt__screen {
  position: relative;
  overflow: hidden;
  display: grid;
  place-items: center;
  height: clamp(112px, 58vh, 196px);
  background: #0d1220;
  border-radius: 8px;
}

.crt__content {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 4px;
  justify-items: center;
  padding: 8px;
  text-align: center;
}

.crt__title {
  margin: 0;
  color: #fff7e6;
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Consolas, "Liberation Mono", monospace;
  font-weight: 700;
  font-size: clamp(16px, 4.2vh, 22px);
  line-height: 1.2;
  letter-spacing: 0.08em;
  text-shadow: 0 0 12px rgba(255, 247, 230, 0.35);
}

.crt__sub {
  margin: 0;
  color: rgba(255, 247, 230, 0.82);
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Consolas, "Liberation Mono", monospace;
  font-weight: 500;
  font-size: clamp(10px, 2.6vh, 12px);
  line-height: 1.4;
  letter-spacing: 0.04em;
}

.crt__band {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  z-index: 2;
  height: 30%;
  pointer-events: none;
  background: linear-gradient(to bottom, transparent, rgba(255, 247, 230, 0.08) 28%, rgba(255, 247, 230, 0.14) 50%, rgba(255, 247, 230, 0.08) 72%, transparent);
  animation-name: crtBand;
  animation-duration: 2s;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

.crt__lines {
  position: absolute;
  inset: 0;
  z-index: 3;
  pointer-events: none;
  background-image: repeating-linear-gradient(to bottom, rgba(23, 20, 26, 0.38) 0 2px, transparent 2px 4px);
  background-size: 100% 4px;
}

.crt__vig {
  position: absolute;
  inset: 0;
  z-index: 4;
  pointer-events: none;
  border-radius: inherit;
  background: radial-gradient(ellipse 130% 105% at 50% 46%, transparent 40%, rgba(23, 20, 26, 0.18) 64%, rgba(23, 20, 26, 0.55) 100%);
}

.crt__cap {
  margin: 0;
  color: #17141a;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.4;
  text-align: center;
}

@keyframes crtBand {
  0% {
    transform: translateY(-110%);
  }
  100% {
    transform: translateY(500%);
  }
}
@media (max-width: 340px) {
  .crt {
    gap: 4px;
  }
  .crt__bezel {
    padding: 8px;
  }
  .crt__cap {
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .crt__band {
    animation: none !important;
  }
}

// CrtScreen — vanilla 판(run/023/demo/02-os-crt-scanline-curve/index.html) 의 React 포트.
// 가로 줄무늬를 타일 하나(4px)로 정의해 background-size 로 반복하고 radial-gradient 타원 비네트를
// 얹는다. 밝은 띠가 translateY 로 위에서 아래로 흐른다. 조작 상태가 없어 그림만 그린다.
import type { CSSProperties } from "react";
import styles from "./CrtScreen.module.scss";

export type CrtScreenProps = {
  duration?: number;
  easing?: string;
  color?: string;
  title?: string;
  subtitle?: string;
  caption?: string;
};

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

export default function CrtScreen(props: CrtScreenProps) {
  const vars: Vars = {
    "--duration": (props.duration ?? 2000) + "ms",
    "--easing": props.easing ?? "ease-out",
    "--color": props.color ?? "#fff7e6"
  };
  return (
    <main className={styles.stage}>
      <figure className={styles.crt} style={vars}>
        <div className={styles.bezel}>
          <div className={styles.screen}>
            <div className={styles.content}>
              <p className={styles.title}>{props.title ?? "레트로 OS"}</p>
              <p className={styles.sub}>{props.subtitle ?? "crt 모니터 효과 — css 만으로"}</p>
            </div>
            <span className={styles.band} aria-hidden="true" />
            <span className={styles.lines} aria-hidden="true" />
            <span className={styles.vig} aria-hidden="true" />
          </div>
        </div>
        <figcaption className={styles.cap}>
          {props.caption ?? "줄무늬 타일 하나와 타원 비네트로 브라운관을 흉내 냈습니다"}
        </figcaption>
      </figure>
    </main>
  );
}