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);
}

.row {
  display: flex;
  align-items: center;
  gap: 20px;
}

.track {
  position: relative;
  width: 3px;
  height: 96px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.15);
}

.dot {
  position: absolute;
  top: 0;
  left: 50%;
  width: 8px;
  height: 8px;
  margin-left: -4px;
  border-radius: 50%;
  background: #3ec9ff;
  box-shadow: 0 0 8px #3ec9ff;
}

@property --intensity {
  syntax: "<number>";
  inherits: false;
  initial-value: 0;
}
.card {
  box-sizing: border-box;
  width: clamp(150px, 44vmin, 200px);
  padding: 20px 16px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  flex-direction: column;
  gap: 12px;
  opacity: calc(0.45 + var(--intensity) * 0.55);
  box-shadow: 0 0 calc(var(--intensity) * 12px) #3ec9ff, 0 0 calc(var(--intensity) * 40px) rgba(62, 201, 255, 0.55);
}

.bar {
  display: block;
  height: 8px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.18);
}

.bar--lg {
  width: 75%;
}

.bar--sm {
  width: 48%;
}

.stage.is-demo .dot {
  animation: move 2s ease-in-out infinite;
}

.stage.is-demo .card:not(.is-live) {
  animation: rise 2s ease-in-out infinite;
}

@keyframes move {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(88px);
  }
}
@keyframes rise {
  0%, 100% {
    --intensity: 0;
  }
  50% {
    --intensity: 1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .dot,
  .stage.is-demo .card:not(.is-live) {
    animation: none;
  }
  .card {
    --intensity: 1;
  }
}