:root {
  --bg: #2f3a2c;
  --bg-deep: #232b21;
  --paper: #fff;
  --accent: #e4c46b;
  --ink: #f2f0e6;
  --arrow-size: 3rem;
}
* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  display: grid;
  grid-template-rows: auto 1fr auto;
  background: radial-gradient(circle at 50% 30%, var(--bg), var(--bg-deep));
  color: var(--ink);
  font-family: Georgia, "Times New Roman", serif;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
}
body.dropping::after {
  content: "Drop PDF to add it";
  position: fixed; inset: 0.5rem;
  display: grid; place-items: center;
  border: 3px dashed var(--accent);
  background: rgba(0,0,0,.55);
  font-size: 1.5rem; z-index: 10;
}

/* Toolbar with the two menus */
.toolbar {
  display: flex; gap: 0.75rem; align-items: center;
  padding: 0.6rem 0.75rem;
  border-bottom: 1px solid rgba(228,196,107,.3);
}
.menu { display: flex; align-items: center; gap: 0.5rem; flex: 1; min-width: 0; }
.menu-label { white-space: nowrap; }
select {
  flex: 1; min-width: 0; max-width: 32rem;
  padding: 0.5rem; font: inherit;
  background: var(--bg-deep); color: var(--ink);
  border: 1px solid var(--accent); border-radius: 4px;
}
.btn {
  padding: 0.5rem 1rem; font: inherit; cursor: pointer;
  background: var(--accent); color: var(--bg-deep);
  border: 1px solid var(--accent); border-radius: 4px;
  white-space: nowrap;
}
.btn:hover:not(:disabled) { background: transparent; color: var(--accent); }
.btn-quiet { background: transparent; color: var(--accent); }
.btn-quiet:hover:not(:disabled) { background: var(--accent); color: var(--bg-deep); }
.btn:disabled { opacity: .35; cursor: default; }

/* Viewer */
.viewer {
  display: grid; grid-template-columns: auto 1fr auto;
  align-items: center; gap: 0.5rem;
  padding: 0.75rem 0.5rem 0; min-height: 0;
}
.stage {
  position: relative; height: 100%; min-height: 0;
  overflow: hidden; touch-action: pan-y; user-select: none;
  display: grid; place-items: center;
}
.book { position: relative; transition: transform var(--flip, 800ms) ease-in-out; }
.slot { position: absolute; top: 0; }
.slot.has-page { background: var(--paper); box-shadow: 0 8px 30px rgba(0,0,0,.45); }
.slot canvas, .face canvas { display: block; width: 100%; height: 100%; pointer-events: none; }
.leaf { position: absolute; top: 0; display: none; transform-origin: left center; transform-style: preserve-3d; z-index: 2; }
.face {
  position: absolute; inset: 0; overflow: hidden;
  background: var(--paper); box-shadow: 0 6px 24px rgba(0,0,0,.4);
  backface-visibility: hidden; -webkit-backface-visibility: hidden;
}
.face.back { transform: rotateY(180deg); }
/* soft shading toward the spine in two-page mode */
.book.double .slot.has-page::after {
  content: ""; position: absolute; top: 0; bottom: 0; width: 7%; pointer-events: none;
}
.book.double #slotL.has-page::after { right: 0; background: linear-gradient(to right, transparent, rgba(0,0,0,.2)); }
.book.double #slotR.has-page::after { left: 0;  background: linear-gradient(to left,  transparent, rgba(0,0,0,.2)); }
.status {
  position: absolute; inset: 0; margin: 0;
  display: grid; place-items: center; text-align: center;
  padding: 1rem; pointer-events: none;
}
.status:empty { display: none; }

.nav {
  width: var(--arrow-size); height: var(--arrow-size);
  border: 2px solid var(--accent); border-radius: 50%;
  background: transparent; color: var(--accent);
  font-size: 2rem; line-height: 1; padding: 0 0 .25rem; cursor: pointer;
  transition: background .15s, color .15s, opacity .15s;
}
.nav:hover:not(:disabled) { background: var(--accent); color: var(--bg-deep); }
.nav:disabled { opacity: .25; cursor: default; }
.nav:focus-visible, .btn:focus-visible, select:focus-visible { outline: 3px solid #fff; outline-offset: 3px; }
.bar { text-align: center; padding: 0.5rem 0 0.75rem; font-size: .95rem; min-height: 2rem; }

@media (max-width: 600px) {
  :root { --arrow-size: 2.25rem; }
  .menu-label { display: none; }
  .toolbar { flex-wrap: wrap; }
  .menu { flex-basis: 100%; }
  .btn { padding: 0.45rem 0.75rem; }
  .viewer { padding: 0.5rem 0.25rem 0; gap: 0.25rem; }
  .nav { font-size: 1.5rem; }
}