:root {
  --bg: #f5f1e8;
  --panel: #fffdf8;
  --ink: #2f2a24;
  --accent: #7a4f2a;
}

* {
  box-sizing: border-box;
}

html, body, .shell {
  height: 100%;
}

body {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  color: var(--ink);
  background: radial-gradient(circle at top, #fff8e6, var(--bg));
}

.shell {
  max-width: 1500px;
  margin: 0 auto;
  padding: 24px;
  display: flex;
  align-items: center;      /* vertical align */
  justify-content: center;  /* optional horizontal align */

  min-height: 100vh;
}

h1 {
  margin-top: 0;
}

.toolbar {
  /* display: grid; */
  display: none;
  grid-template-columns: auto 1fr auto;
  gap: 12px;
  align-items: center;
  margin-bottom: 20px;
}

input,
button {
  border: 1px solid #c8b8a3;
  border-radius: 8px;
  padding: 10px 12px;
  font: inherit;
}

button {
  cursor: pointer;
  background: #fff;
}

.book-wrap {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
}

.book {
  min-height: 480px;
  background: var(--panel);
  border: 1px solid #dfd3c2;
  border-radius: 16px;
  box-shadow: 0 16px 45px rgba(78, 62, 40, 0.18);
  padding: 16px;
  perspective: 1200px;
}

.spread {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  transform-origin: center;
}

.spread.flipping-next {
  animation: flipNext 380ms ease;
}

.spread.flipping-prev {
  animation: flipPrev 380ms ease;
}

canvas {
  width: 100%;
  height: auto;
  border-radius: 10px;
  background: white;
  border: 1px solid #e5ddd2;
}

.status {
  margin: 10px 0 0;
}

.nav {
  min-width: 70px;
}

@keyframes flipNext {
  0% { transform: rotateY(0deg) scale(1); opacity: 1; }
  50% { transform: rotateY(-15deg) scale(0.99); opacity: 0.75; }
  100% { transform: rotateY(0deg) scale(1); opacity: 1; }
}

@keyframes flipPrev {
  0% { transform: rotateY(0deg) scale(1); opacity: 1; }
  50% { transform: rotateY(15deg) scale(0.99); opacity: 0.75; }
  100% { transform: rotateY(0deg) scale(1); opacity: 1; }
}

@media (max-width: 800px) {
  .book-wrap {
    grid-template-columns: 1fr;
  }

  .spread {
    grid-template-columns: 1fr;
  }
}