/* Paleta extraída de referencias/roteiro visual..pdf (Esquema de Cores) */
:root {
  color-scheme: light;
  --paper: #F1EDE3;
  --page: #F8F6F0;

  /* fase 1 — normal */
  --f1-a: #2E422B;
  --f1-b: #69554A;
  --f1-c: #AEAD8D;
  --f1-d: #BFC0C0;
  /* fase 2 — doente */
  --f2-a: #FF1313;
  --f2-b: #52AEB7;
  --f2-c: #F217FE;
  --f2-d: #FF900E;
  /* fase 3 — caos */
  --f3-a: #FF3B3F;
  --f3-b: #4CC9F0;
  --f3-c: #7963FF;
  --f3-d: #52B788;
  /* fase 4 — cura */
  --f4-a: #CDEAC0;
  --f4-b: #E0FBFC;
  --f4-c: #B8C1EC;
  --f4-d: #F7B7F6;

  --ink: var(--f1-a);
  --ink-soft: var(--f1-b);
  --line: color-mix(in srgb, var(--f1-d) 55%, transparent);

  --accent: var(--f3-a);
  --accent-text: color-mix(in srgb, var(--f3-a) 68%, black 32%);
  --good: var(--f3-d);
  --good-text: color-mix(in srgb, var(--f3-d) 55%, black 45%);

  /* cor da cena atual: sobrescrita via JS com a paleta própria de cada música
     (extraída de referencias/roteiro visual..pdf); cai no acento padrão fora das faixas */
  --scene-accent: var(--accent);
  /* fundo do site tingido com a cor da cena; a página do livro (--page) fica
     neutra, como papel de verdade, só o entorno acompanha o clima da faixa */
  --page-wash: color-mix(in srgb, var(--scene-accent) 12%, var(--paper) 88%);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background: var(--page-wash);
  transition: background-color .6s ease;
  font-family: "Iowan Old Style", "Palatino Linotype", Georgia, "Liberation Serif", serif;
}

button, input { font: inherit; }

/* ---- mobile-first base ---- */

.app {
  width: 100%;
  margin: 0 auto;
  padding: 20px 12px 40px;
}

.topnav {
  display: flex;
  gap: 4px;
  margin-bottom: 18px;
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: .72rem;
  text-transform: uppercase;
  letter-spacing: .08em;
}
.topnav a {
  padding: 8px 12px;
  min-height: 36px;
  display: flex;
  align-items: center;
  color: var(--ink-soft);
  text-decoration: none;
  border: 1px solid transparent;
  border-radius: 2px;
}
.topnav a[aria-current="page"] {
  color: var(--ink);
  border-color: var(--ink);
}
.topnav a:hover { color: var(--ink); }

.intro { margin: 0 auto; width: 100%; }
.intro h1 {
  margin: 2px 0 10px;
  font-family: "Unna", "Iowan Old Style", Georgia, serif;
  font-weight: 700;
  font-size: clamp(2.1rem, 11vw, 4.6rem);
  letter-spacing: .01em;
}

.roteiro {
  margin: 18px 0 22px;
  height: 6px;
  border-radius: 3px;
  background: linear-gradient(to right,
    var(--f1-a) 0 6.25%, var(--f1-b) 6.25% 12.5%, var(--f1-c) 12.5% 18.75%, var(--f1-d) 18.75% 25%,
    var(--f2-a) 25% 31.25%, var(--f2-b) 31.25% 37.5%, var(--f2-c) 37.5% 43.75%, var(--f2-d) 43.75% 50%,
    var(--f3-a) 50% 56.25%, var(--f3-b) 56.25% 62.5%, var(--f3-c) 62.5% 68.75%, var(--f3-d) 68.75% 75%,
    var(--f4-a) 75% 81.25%, var(--f4-b) 81.25% 87.5%, var(--f4-c) 87.5% 93.75%, var(--f4-d) 93.75% 100%
  );
}

.reader {
  border: 1px solid color-mix(in srgb, var(--scene-accent) 30%, var(--line));
  border-radius: 4px;
  padding: 10px;
  background: var(--page);
  transition: border-color .5s ease;
}

.scene-bar {
  height: 5px;
  border-radius: 3px;
  margin-bottom: 14px;
  background: var(--scene-accent);
  transition: background-color .5s ease;
}

.toolbar {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  align-items: center;
  margin: 0 auto 16px;
}
.toolbar #position { grid-column: 1 / -1; grid-row: 1; order: -1; }

button {
  min-height: 44px;
  border: 1px solid var(--ink);
  border-radius: 2px;
  padding: 10px 12px;
  color: var(--ink);
  background: transparent;
  text-transform: uppercase;
  letter-spacing: .06em;
  font-size: .72rem;
  cursor: pointer;
  transition: background .15s, color .15s;
}
button:hover:not(:disabled) { background: var(--ink); color: var(--page); }
button:active:not(:disabled) { background: var(--accent); border-color: var(--accent); color: var(--page); }
button:disabled { opacity: .32; cursor: default; }
.position {
  text-align: center;
  color: var(--ink-soft);
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: .74rem;
  letter-spacing: .01em;
}

.book-stage {
  width: 100%;
  margin: 0 auto;
  perspective: 2200px;
}

.book {
  position: relative;
  width: 100%;
  aspect-ratio: 2 / 1;
  filter: drop-shadow(0 14px 18px rgba(32, 29, 26, .22));
}

#bookCanvas {
  display: block;
  width: 100%;
  aspect-ratio: 2 / 1;
  touch-action: none;
  cursor: grab;
  border-radius: 3px;
  background: color-mix(in srgb, var(--scene-accent) 6%, var(--paper) 94%);
  transition: background-color .6s ease;
}
#bookCanvas:active { cursor: grabbing; }

.page, .face {
  position: absolute;
  top: 0;
  width: 50%;
  height: 100%;
  overflow: hidden;
  background: var(--page);
}

.page img, .face img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page.empty img, .face.empty img { display: none; }
.page.empty, .face.empty {
  background: repeating-linear-gradient(135deg, var(--f1-c), var(--f1-c) 12px, var(--f1-d) 12px, var(--f1-d) 24px);
}

.left-page { left: 0; border-radius: 3px 0 0 3px; }
.right-page { right: 0; border-radius: 0 3px 3px 0; }
.left-page { box-shadow: inset -16px 0 24px -26px rgba(0,0,0,.55); }
.right-page { box-shadow: inset 16px 0 24px -26px rgba(0,0,0,.55); }

.spine {
  position: absolute;
  z-index: 8;
  left: calc(50% - 1px);
  top: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(to right, rgba(0,0,0,.22), rgba(255,255,255,.3), rgba(0,0,0,.26));
  pointer-events: none;
}

.page-number {
  position: absolute;
  bottom: 6px;
  min-width: 22px;
  padding: 2px 5px;
  border: 1px solid color-mix(in srgb, var(--scene-accent) 55%, rgba(32,29,26,.5));
  border-radius: 1px;
  color: var(--ink);
  background: color-mix(in srgb, var(--page) 82%, transparent);
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: .58rem;
  text-align: center;
  transition: border-color .5s ease;
}
.left-page .page-number, .flip-sheet.prev .front .page-number { left: 6px; }
.right-page .page-number, .flip-sheet.next .front .page-number { right: 6px; }

.flip-sheet {
  position: absolute;
  z-index: 7;
  top: 0;
  width: 50%;
  height: 100%;
  display: none;
  transform-style: preserve-3d;
  will-change: transform;
}
.flip-sheet.active { display: block; }
.flip-sheet.next { left: 50%; transform-origin: left center; }
.flip-sheet.prev { left: 0; transform-origin: right center; }
.flip-sheet.turn-next { animation: turnNext .7s cubic-bezier(.6,.02,.28,1) forwards; }
.flip-sheet.turn-prev { animation: turnPrev .7s cubic-bezier(.6,.02,.28,1) forwards; }

.face {
  inset: 0;
  width: 100%;
  backface-visibility: hidden;
  box-shadow: 0 0 16px rgba(32,29,26,.18);
}
.face.back { transform: rotateY(180deg); }

@keyframes turnNext {
  0% { transform: rotateY(0deg); }
  100% { transform: rotateY(-180deg); }
}
@keyframes turnPrev {
  0% { transform: rotateY(0deg); }
  100% { transform: rotateY(180deg); }
}

.page-descriptions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  margin: 12px auto 0;
  background: var(--line);
}
.page-descriptions > div { min-height: 44px; padding: 6px 8px; background: var(--page-wash); transition: background-color .6s ease; }
.page-descriptions > div:first-child { text-align: right; }
.page-descriptions span {
  display: block;
  margin-bottom: 2px;
  color: var(--ink-soft);
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: .6rem;
  text-transform: uppercase;
  letter-spacing: .08em;
}
.page-descriptions strong { font-size: .74rem; font-weight: 600; line-height: 1.3; }

.spread-alert {
  min-height: 22px;
  margin: 12px auto 0;
  color: var(--ink-soft);
  text-align: center;
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: .72rem;
}
.spread-alert.good { color: var(--good-text); }
.spread-alert.warning { color: var(--accent-text); }

.jump {
  display: grid;
  grid-template-columns: 1fr;
  gap: 7px;
  align-items: center;
  margin: 20px auto 0;
  color: var(--ink-soft);
  font-size: .8rem;
}
.jump input { width: 100%; accent-color: var(--scene-accent); min-height: 32px; transition: accent-color .5s ease; }
.hint { margin: 16px 0 0; color: var(--ink-soft); text-align: center; font-size: .75rem; }

/* ---- tablet / desktop ---- */
@media (min-width: 641px) {
  .app { width: min(1180px, 96vw); padding: 48px 0 60px; }
  .intro { width: min(960px, 94vw); }
  .roteiro { max-width: min(960px, 94vw); margin: 22px auto 26px; height: 7px; }

  .reader { border-radius: 6px; padding: clamp(14px, 3vw, 30px); }
  .toolbar {
    grid-template-columns: 150px 1fr 150px;
    gap: 16px;
    width: min(100%, 1000px);
    margin: 0 auto 24px;
  }
  .toolbar #position { grid-column: auto; grid-row: auto; order: 0; }

  .book-stage { width: min(100%, 1000px); }

  .page-descriptions { grid-template-columns: 1fr 1fr; gap: 2px; width: min(100%, 1000px); }
  .page-descriptions > div { min-height: 52px; padding: 8px 13px; }
  .page-descriptions strong { font-size: clamp(.72rem, 1.5vw, .9rem); }

  .spread-alert { width: min(100%, 1000px); font-size: .78rem; }

  .jump { grid-template-columns: auto 1fr; gap: 14px; width: min(100%, 760px); margin: 26px auto 0; }
}

@media (prefers-reduced-motion: reduce) {
  .flip-sheet.turn-next, .flip-sheet.turn-prev { animation-duration: .01s; }
}