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);
}

.layout {
  display: flex;
  width: min(90vw, 340px);
  height: min(50vw, 150px);
  border-radius: 16px;
  overflow: hidden;
  background: #ffffff;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.rail {
  flex: none;
  width: 96px;
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 12px 8px;
  background: #17141a;
  transform: translateX(0);
  transition: transform 220ms ease-out;
}

.rail__link {
  padding: 4px 8px;
  border-radius: 4px;
  color: #ffffff;
  text-decoration: none;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.2;
  font-family: inherit;
}
.rail__link:hover, .rail__link:focus-visible {
  color: #fff7e6;
  background: rgba(255, 255, 255, 0.12);
}

.rail.is-hidden {
  transform: translateX(-100%);
}

.content {
  flex: 1;
  overflow-y: auto;
  box-sizing: border-box;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  color: #17141a;
}
.content p {
  margin: 0;
  font-size: clamp(10px, 3vmin, 12px);
  line-height: 1.5;
  opacity: 0.8;
}

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

@keyframes rail-loop {
  0%, 100% {
    transform: translateX(0);
  }
  40%, 70% {
    transform: translateX(-100%);
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .rail {
    animation: none;
  }
  .rail {
    transition-duration: 1ms;
  }
}