:root {
  --ink: #182433;
  --muted: #607084;
  --primary: #1f8a5b;
  --sky: #2f6fed;
  --paper: #fffdf8;
  --line: rgba(24, 36, 51, 0.1);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: "Noto Sans SC", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(ellipse at top left, #d9fff0 0, transparent 42%),
    radial-gradient(ellipse at top right, #d9e8ff 0, transparent 40%),
    linear-gradient(180deg, #f4faf7 0%, #fff8ef 100%);
}

.view { min-height: 100vh; }
.hero {
  text-align: center;
  padding: 48px 20px 12px;
}
.hero .home {
  display: inline-block;
  margin-bottom: 18px;
  color: var(--sky);
  text-decoration: none;
  font-family: Fredoka, "Noto Sans SC", sans-serif;
  font-weight: 600;
}
.hero h1 {
  margin: 0 0 8px;
  font-family: Fredoka, "Noto Sans SC", sans-serif;
  font-size: clamp(2rem, 5vw, 2.8rem);
}
.hero p { margin: 0; color: var(--muted); }

.picker {
  width: min(440px, calc(100% - 32px));
  margin: 28px auto;
  background: rgba(255,255,255,.86);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 22px;
  display: grid;
  gap: 14px;
  box-shadow: 0 16px 40px rgba(24,36,51,.06);
}
.picker label { display: grid; gap: 6px; text-align: left; }
.picker span { font-size: .92rem; color: var(--muted); }
.picker select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
  font: inherit;
  background: #fff;
}
.hint { margin: 0; color: var(--muted); font-size: .9rem; min-height: 1.2em; }

.btn {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--ink);
  border-radius: 12px;
  padding: 12px 16px;
  font: inherit;
  cursor: pointer;
}
.btn.primary {
  background: var(--primary);
  color: #fff;
  border-color: transparent;
  font-weight: 600;
}
.btn.ghost { background: transparent; }
.btn:disabled { opacity: .45; cursor: not-allowed; }

.reader-bar {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 10px;
  align-items: center;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  background: rgba(255,255,255,.75);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 5;
}
.reader-title {
  font-family: Fredoka, "Noto Sans SC", sans-serif;
  font-weight: 600;
  text-align: center;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.page-indicator { color: var(--muted); font-size: .9rem; }

.reader-stage {
  width: min(960px, 100%);
  margin: 0 auto;
  padding: 16px;
  display: grid;
  gap: 16px;
  justify-items: center;
}

.book-stage {
  position: relative;
  width: 100%;
  height: min(68vh, 700px);
  perspective: 1200px;
  transform-style: preserve-3d;
  overflow: hidden;
}

.stage-page {
  position: absolute;
  inset: 0;
  display: grid;
  grid-template-rows: 1fr auto;
  gap: 10px;
  justify-items: center;
  align-content: stretch;
  padding: 4px;
  border-radius: 16px;
  background: var(--paper);
  border: 1px solid var(--line);
  box-shadow: 0 14px 36px rgba(24, 36, 51, 0.1);
  overflow: hidden;
}

.stage-page--base {
  z-index: 1;
}

/* 3D 翻书：旧页顶层，旋转翻走露出下层新页 */
.stage-page--flip {
  z-index: 3;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  pointer-events: none;
  will-change: transform;
  opacity: 1;
}

/* .stage-page 的 display:grid 会压过 [hidden] 默认行为，必须强制隐藏 */
.stage-page--flip[hidden] {
  display: none !important;
}

.stage-page--flip.is-done {
  display: none !important;
  opacity: 0 !important;
  visibility: hidden !important;
}

.stage-img {
  width: 100%;
  height: min(52vh, 560px);
  max-height: none;
  object-fit: contain;
  display: block;
  border-radius: 12px;
  background: #f7f2ea;
}

.stage-text {
  margin: 0;
  padding: 4px 12px 10px;
  font-family: Fredoka, "Noto Sans SC", sans-serif;
  font-size: clamp(1.5rem, 3.6vw, 2.2rem);
  text-align: center;
  line-height: 1.35;
  width: 100%;
  min-height: 2.8em;
}

.page-flip--next {
  transform-origin: left center;
  animation: pbFlipNext 0.55s ease-in-out forwards;
}

.page-flip--prev {
  transform-origin: right center;
  animation: pbFlipPrev 0.55s ease-in-out forwards;
}

@keyframes pbFlipNext {
  from { transform: rotateY(0deg); }
  to { transform: rotateY(-90deg); }
}

@keyframes pbFlipPrev {
  from { transform: rotateY(0deg); }
  to { transform: rotateY(90deg); }
}

@media (prefers-reduced-motion: reduce) {
  .page-flip--next,
  .page-flip--prev {
    animation-duration: 0.01ms !important;
  }
}

.reader-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 4px;
  z-index: 6;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 22px;
  transform: translateX(-50%);
  background: #182433;
  color: #fff;
  padding: 10px 16px;
  border-radius: 999px;
  z-index: 30;
}

@media (max-width: 640px) {
  .reader-bar { grid-template-columns: 1fr; justify-items: center; }
  .book-stage { height: min(62vh, 560px); }
  .stage-img { height: min(42vh, 420px); }
}