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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.bp-book {
  position: relative;
  width: 150px;
  height: 108px;
  perspective: 900px;
}

.bp-page-under,
.bp-page__face {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 16px;
  font: 700 22px/1 -apple-system, "Segoe UI", sans-serif;
  color: #17141a;
}

.bp-page-under {
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.bp-page {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transform-origin: right center;
  transition: transform 600ms cubic-bezier(0.2, 0.8, 0.2, 1), box-shadow 600ms cubic-bezier(0.2, 0.8, 0.2, 1);
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.bp-page__face {
  backface-visibility: hidden;
}

.bp-page__face--front {
  background: #fff7e6;
}

.bp-page__face--back {
  background: rgba(23, 20, 26, 0.78);
  color: #fff7e6;
  transform: rotateY(180deg);
}

@keyframes bp-turn {
  0%, 30% {
    transform: rotateY(0);
  }
  70%, 100% {
    transform: rotateY(-155deg);
  }
}
.bp-book.is-demo .bp-page {
  animation: bp-turn 1560ms cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .bp-book.is-demo .bp-page {
    animation: none !important;
    transition: none !important;
    transform: none !important;
  }
}