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);
}

.stage {
  position: relative;
}

.page-mock {
  position: absolute;
  inset: 24px 40px auto 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.page-mock__line {
  display: block;
  height: 8px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.14);
}

.page-mock__line:nth-child(1) {
  width: 72%;
}

.page-mock__line:nth-child(2) {
  width: 88%;
}

.page-mock__line:nth-child(3) {
  width: 56%;
}

.totop {
  position: absolute;
  right: 24px;
  bottom: 24px;
  width: 48px;
  height: 48px;
  border: 0;
  border-radius: 999px;
  background: #ffd23f;
  display: grid;
  place-items: center;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  cursor: pointer;
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 260ms ease-out, transform 260ms ease-out;
}

.totop.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.totop.is-demo {
  animation: totop-loop 2s ease-out infinite;
}

@keyframes totop-loop {
  0%, 100% {
    opacity: 0;
    transform: translateY(16px);
  }
  20%, 80% {
    opacity: 1;
    transform: translateY(0);
  }
}
.totop__arrow {
  width: 22px;
  height: 22px;
  fill: none;
  stroke: #17141a;
  stroke-width: 2.4;
  stroke-linecap: round;
  stroke-linejoin: round;
}

@media (prefers-reduced-motion: reduce) {
  .totop, .totop.is-demo {
    transition: none;
    animation: none;
    opacity: 1;
    transform: translateY(0);
  }
}