html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  min-height: 100vh;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.sentinel {
  position: absolute;
  top: 0;
  height: 1px;
  width: 1px;
}

.head {
  position: sticky;
  top: 0;
  height: 56px;
  display: flex;
  align-items: center;
  padding: 0 clamp(16px, 5vw, 24px);
  background: #ffffff;
}
.head__logo {
  color: #17141a;
  font-weight: 800;
  font-size: 18px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.04em;
}
.head__shadow {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -48px;
  height: 48px;
  background: linear-gradient(rgba(23, 20, 26, 0.85), rgba(23, 20, 26, 0));
  opacity: 0;
  transition: opacity 220ms ease-out;
}
.head.is-scrolled .head__shadow {
  opacity: 1;
}

.head.is-demo .head__shadow {
  animation: shadow-loop 2s ease-out infinite;
}

@keyframes shadow-loop {
  0%, 5% {
    opacity: 0;
  }
  40%, 60% {
    opacity: 1;
  }
  95%, 100% {
    opacity: 0;
  }
}
.page {
  padding: 24px 24px 0;
}

.page__line {
  height: 12px;
  margin: 0 0 14px;
  border-radius: 4px;
  background: rgba(23, 20, 26, 0.12);
}
.page__line.short {
  width: 60%;
}

@media (prefers-reduced-motion: reduce) {
  .head__shadow {
    transition: none;
  }
  .head.is-demo .head__shadow {
    animation: none !important;
    opacity: 1;
  }
}