03Streaming caret blink

<main class="stage">
  <p class="cr-line is-demo">The border light rotates once around <span class="cr-tail">the card</span><span class="cr-caret"></span></p>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: 530ms;
$easing: steps(1);
$color: $subject-cream;

@include stage($stage-orange);

.cr-line {
  width: min(300px, 88vw);
  margin: 0;
  padding: $sp-4 $sp-5;
  border-radius: $r-card;
  box-sizing: border-box;
  background: rgba(255, 255, 255, .12);
  color: $subject-ink;   // 주황 무대 위 글자 — AA 4.5 (blog-design 글자 대비)
  font: 500 14px/1.5 -apple-system, "Segoe UI", sans-serif;
}

.cr-caret {
  display: inline-block;
  width: $sp-2;
  height: 1em;
  margin-left: $sp-1;
  vertical-align: -0.2em;
  background: $subject-ink;   // 글자와 같은 색 (주황 무대 위 AA 4.5)
}

// 마지막으로 방금 도착한 단어 — 커서와 같은 박자로 깜빡여 "지금 여기"를 눈에 띄게 한다
.cr-tail { opacity: 1; }

// 실사용: 새 토큰이 도착하는 동안 항상 깜빡인다
@keyframes cr-blink {
  0%, 49%  { opacity: 1; }
  50%, 100% { opacity: .25; }
}
.cr-line.is-demo .cr-caret,
.cr-line.is-demo .cr-tail {
  animation: cr-blink $duration $easing infinite;
}

@media (prefers-reduced-motion: reduce) {
  .cr-line.is-demo .cr-caret,
  .cr-line.is-demo .cr-tail {
    animation: none !important;
    opacity: 1 !important;
  }
}

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);
}

.cr-line {
  width: min(300px, 88vw);
  margin: 0;
  padding: 16px 20px;
  border-radius: 16px;
  box-sizing: border-box;
  background: rgba(255, 255, 255, 0.12);
  color: #17141a;
  font: 500 14px/1.5 -apple-system, "Segoe UI", sans-serif;
}

.cr-caret {
  display: inline-block;
  width: 8px;
  height: 1em;
  margin-left: 4px;
  vertical-align: -0.2em;
  background: #17141a;
}

.cr-tail {
  opacity: 1;
}

@keyframes cr-blink {
  0%, 49% {
    opacity: 1;
  }
  50%, 100% {
    opacity: 0.25;
  }
}
.cr-line.is-demo .cr-caret,
.cr-line.is-demo .cr-tail {
  animation: cr-blink 530ms steps(1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .cr-line.is-demo .cr-caret,
  .cr-line.is-demo .cr-tail {
    animation: none !important;
    opacity: 1 !important;
  }
}

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

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

export interface StreamingCaretProps {
  duration?: string;
  easing?: string;
  color?: string;
  text?: string;
  tail?: string;
}

export default function StreamingCaret({
  duration = "530ms",
  easing = "steps(1)",
  color = "#fff7e6",
  text = "The border light rotates once around ",
  tail = "the card",
}: StreamingCaretProps) {
  const style: Vars = {
    "--duration": duration,
    "--easing": easing,
    "--color": color,
  };
  return (
    <p className={styles.line} style={style}>
      {text}
      <span className={styles.tail}>{tail}</span>
      <span className={styles.caret} />
    </p>
  );
}