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);
}

@property --hue {
  syntax: "<number>";
  inherits: false;
  initial-value: 262;
}
.badge {
  display: block;
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: #17141a;
  box-shadow: 0 0 16px #8b5cf6, 0 0 40px rgba(139, 92, 246, 0.5);
}

@supports (background: hsl(var(--hue), 100%, 50%)) {
  .badge {
    box-shadow: 0 0 16px hsl(var(--hue), 90%, 62%), 0 0 40px hsl(var(--hue), 90%, 55%, 0.55);
  }
}
.stage.is-demo .badge {
  animation: cycle 2s linear infinite;
}

@keyframes cycle {
  from {
    --hue: 0;
  }
  to {
    --hue: 360;
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .badge {
    animation: none;
    --hue: 262;
  }
}