강제 색상 모드

<div class="stage">
  <div class="card" id="card">
    <div class="ico" id="ico"></div>
    <div class="ln"></div>
    <div class="ln short"></div>
    <div class="badge" id="badge">default</div>
  </div>
</div>

.stage{width:64%;height:82%;display:grid;place-items:center}
.card{width:100%;height:100%;border-radius:14px;border:1px solid var(--line);background:var(--surface);padding:10%;display:flex;flex-direction:column;gap:10%;transition:background .4s ease,border-color .4s ease}
.card.forced{background:#000;border:2px solid #fff}
.ico{width:26%;height:26%;border-radius:8px;background:linear-gradient(135deg,var(--accent),var(--accent-2));transition:opacity .4s ease,background .4s ease,border-color .4s ease;border:2px solid transparent}
.card.forced .ico{background:transparent;border-color:#ff0}
.ln{height:10px;border-radius:5px;background:var(--muted);opacity:.3;transition:background .4s ease,opacity .4s ease}
.card.forced .ln{background:#fff;opacity:1}
.short{width:55%}
.badge{margin-top:auto;font:700 10px/1 ui-monospace,monospace;color:var(--muted)}
.card.forced .badge{color:#0ff}

const card = document.getElementById('card');
const badge = document.getElementById('badge');
function toggle() {
  const on = card.classList.toggle('forced');
  badge.textContent = on ? 'forced-colors: active' : 'default';
}
setInterval(toggle, 1900);