/* ==========================================================================
   Estructura de la aplicación: panel lateral, visor, barra y buscador.
   ========================================================================== */

:root {
  --bg: #14161c;
  --bg-soft: #1c1f27;
  --bg-line: #2a2f3a;
  --ink: #e9ecf3;
  --ink-dim: #9aa3b5;
  --accent: #5b9cff;
  --accent-ink: #08111f;
  --radius: 10px;
  --toolbar-h: 52px;
  --sidebar-w: 320px;
  --shadow: 0 8px 28px -10px rgba(0, 0, 0, 0.7);
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
  margin: 0;
}

body {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  grid-template-rows: var(--toolbar-h) 1fr;
  grid-template-areas:
    'sidebar toolbar'
    'sidebar stage';
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.5 system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  overflow: hidden;
}

/* Sin esto, el ancho mínimo automático de los hijos de una rejilla ensancha la
   columna 1fr por culpa del contenido y aparece scroll horizontal. */
body > * {
  min-width: 0;
}

/* El panel lateral se muestra y se oculta empujando el resto. */
body:not(.sidebar-open) {
  grid-template-columns: 0 1fr;
}

body {
  --panel-shadow: 0 0 0 rgba(0, 0, 0, 0);
}

body.sidebar-open .sidebar {
  box-shadow: var(--shadow);
}

/* --- Barra de herramientas ---------------------------------------------- */

.toolbar {
  grid-area: toolbar;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 0 12px;
  background: var(--bg-soft);
  border-bottom: 1px solid var(--bg-line);
  overflow: hidden;
  z-index: 20;
}

.toolbar__group {
  display: flex;
  align-items: center;
  gap: 4px;
  min-width: 0;
  flex: 0 1 auto;
}

.toolbar__group--center {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

.toolbar__sep {
  width: 1px;
  height: 20px;
  margin: 0 5px;
  background: var(--bg-line);
}

.btn {
  display: grid;
  place-items: center;
  min-width: 32px;
  height: 32px;
  padding: 0 8px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--ink-dim);
  font: inherit;
  font-size: 16px;
  line-height: 1;
  text-decoration: none;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.btn:hover:not(:disabled) {
  background: #262b36;
  color: var(--ink);
}

.btn:disabled {
  opacity: 0.32;
  cursor: default;
}

.btn.is-active {
  background: var(--accent);
  color: var(--accent-ink);
}

.btn:focus-visible,
.sidebar__tab:focus-visible,
.sidebar__close:focus-visible,
.outline__link:focus-visible,
.thumb:focus-visible,
.search__input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.btn svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

.toolbar__position,
.toolbar__zoom {
  min-width: 8ch;
  padding: 0 4px;
  color: var(--ink-dim);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
  text-align: center;
  white-space: nowrap;
}

.toolbar__zoom {
  cursor: pointer;
  border-radius: 6px;
  padding: 4px 6px;
}

.toolbar__zoom:hover {
  background: #262b36;
  color: var(--ink);
}

.toolbar__zoom.is-custom {
  color: var(--accent);
}

/* --- Panel lateral -------------------------------------------------------- */

.sidebar {
  grid-area: sidebar;
  display: flex;
  flex-direction: column;
  min-width: 0;
  overflow: hidden;
  background: var(--bg-soft);
  border-right: 1px solid var(--bg-line);
}

body:not(.sidebar-open) .sidebar {
  visibility: hidden;
}

.sidebar__tabs {
  display: flex;
  gap: 2px;
  padding: 8px 8px 0;
  border-bottom: 1px solid var(--bg-line);
}

.sidebar__tab {
  flex: 1;
  padding: 8px 10px;
  border: 0;
  border-bottom: 2px solid transparent;
  background: transparent;
  color: var(--ink-dim);
  font: inherit;
  font-size: 13px;
  cursor: pointer;
}

.sidebar__tab:hover {
  color: var(--ink);
}

.sidebar__tab.is-active {
  color: var(--ink);
  border-bottom-color: var(--accent);
}

/* Cierre propio del panel: en móvil el panel tapa su botón de la barra. */
.sidebar__close {
  flex: none;
  align-self: center;
  width: 30px;
  height: 30px;
  margin-left: auto;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--ink-dim);
  font-size: 15px;
  line-height: 1;
  cursor: pointer;
}

.sidebar__close:hover {
  background: #262b36;
  color: var(--ink);
}

.sidebar__body {
  position: relative;
  flex: 1;
  min-height: 0;
}

.sidebar__panel {
  position: absolute;
  inset: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 8px;
  display: none;
}

.sidebar__panel.is-active {
  display: block;
}

.sidebar__status {
  margin: 16px 8px;
  color: var(--ink-dim);
  font-size: 13px;
  text-align: center;
}

/* Índice */

.outline {
  margin: 0;
  padding: 0;
  list-style: none;
}

.outline .outline {
  padding-left: 12px;
}

.outline__link {
  display: block;
  width: 100%;
  padding: 6px 8px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--ink-dim);
  font: inherit;
  font-size: 13px;
  line-height: 1.35;
  text-align: left;
  cursor: pointer;
}

.outline__link:hover:not(:disabled) {
  background: #262b36;
  color: var(--ink);
}

.outline__link:disabled {
  opacity: 0.5;
  cursor: default;
}

.outline__link.is-current {
  background: rgba(91, 156, 255, 0.16);
  color: var(--ink);
  box-shadow: inset 2px 0 0 var(--accent);
}

.outline__item[data-depth='0'] > .outline__link {
  color: var(--ink);
  font-weight: 500;
}

/* Miniaturas */

.thumbs {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 10px;
}

.thumb {
  display: grid;
  gap: 4px;
  justify-items: center;
  width: 100%;
  padding: 6px;
  border: 2px solid transparent;
  border-radius: 8px;
  background: transparent;
  color: var(--ink-dim);
  font: inherit;
  font-size: 11px;
  cursor: pointer;
}

.thumb:hover {
  background: #262b36;
}

.thumb.is-current {
  border-color: var(--accent);
}

.thumb__frame {
  display: grid;
  place-items: center;
  width: 100%;
  aspect-ratio: 596 / 842;
  background: #fff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.45);
  overflow: hidden;
}

.thumb__canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.thumb__label {
  font-variant-numeric: tabular-nums;
}

.thumb.is-current .thumb__label {
  color: var(--ink);
}

/* --- Buscador ------------------------------------------------------------- */

.search {
  position: fixed;
  top: calc(var(--toolbar-h) + 10px);
  right: 14px;
  z-index: 40;
  width: min(440px, calc(100vw - 28px));
  padding: 8px;
  border: 1px solid var(--bg-line);
  border-radius: var(--radius);
  background: var(--bg-soft);
  box-shadow: var(--shadow);
}

.search__field {
  display: flex;
  align-items: center;
  gap: 6px;
}

.search__icon {
  flex: none;
  width: 16px;
  height: 16px;
  margin-left: 4px;
  fill: var(--ink-dim);
}

.search__input {
  flex: 1;
  min-width: 0;
  padding: 6px 2px;
  border: 0;
  background: transparent;
  color: var(--ink);
  font: inherit;
  font-size: 14px;
}

.search__input:focus {
  outline: none;
}

.search__input::placeholder {
  color: var(--ink-dim);
}

.search__count {
  flex: none;
  min-width: 7ch;
  color: var(--ink-dim);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.search__btn {
  flex: none;
  width: 26px;
  height: 26px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--ink-dim);
  font: inherit;
  font-size: 14px;
  cursor: pointer;
}

.search__btn:hover {
  background: #262b36;
  color: var(--ink);
}

/* --- Visor ---------------------------------------------------------------- */

.stage {
  grid-area: stage;
  position: relative;
  overflow: auto;
  display: grid;
  place-items: center;
  padding: 24px;
  background:
    radial-gradient(120% 90% at 50% 0%, #1e222b 0%, var(--bg) 70%);
  /* Sin `stable`: reservar el hueco de la barra descentra el libro unos
     píxeles a la izquierda aunque no haya nada que desplazar. */
  scrollbar-gutter: auto;
}

.book {
  margin: auto;
}

/* --- Carga ---------------------------------------------------------------- */

.loader {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: grid;
  place-content: center;
  justify-items: center;
  gap: 18px;
  padding: 24px;
  background: var(--bg);
  transition: opacity 0.35s ease, visibility 0.35s;
}

.loader.is-hidden {
  opacity: 0;
  visibility: hidden;
}

.loader__title {
  margin: 0;
  font-size: 17px;
  font-weight: 600;
}

.loader__track {
  width: min(320px, 70vw);
  height: 3px;
  overflow: hidden;
  border-radius: 3px;
  background: var(--bg-line);
}

.loader__bar {
  width: 0;
  height: 100%;
  background: var(--accent);
  transition: width 0.2s ease;
}

.loader__error {
  max-width: 46ch;
  text-align: center;
}

.loader__error h1 {
  margin: 0 0 8px;
  font-size: 18px;
}

.loader__error p {
  margin: 0;
  color: var(--ink-dim);
  font-size: 14px;
  word-break: break-word;
}

/* --- Adaptación a pantallas pequeñas -------------------------------------- */

@media (max-width: 900px) {
  :root {
    --sidebar-w: 280px;
  }
}

@media (max-width: 720px) {
  :root {
    --toolbar-h: 48px;
  }

  body {
    grid-template-columns: 0 1fr;
  }

  /* El lateral se superpone en lugar de empujar el visor. */
  .sidebar {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    width: min(86vw, var(--sidebar-w));
    z-index: 30;
    transform: translateX(-100%);
    transition: transform 0.2s ease;
  }

  body.sidebar-open .sidebar {
    transform: none;
    visibility: visible;
  }

  .toolbar__group--center {
    position: static;
    transform: none;
  }

  .toolbar__group--end,
  .toolbar__sep {
    display: none;
  }

  .toolbar__position {
    min-width: 6ch;
    font-size: 12px;
  }

  .search {
    top: calc(var(--toolbar-h) + 6px);
    right: 6px;
    left: 6px;
    width: auto;
  }
}

@media (max-width: 560px) {
  /* En pantallas estrechas se retiran los botones menos usados para que la
     barra siempre quepa sin scroll horizontal. */
  [data-act='fit'],
  [data-act='fullscreen'] {
    display: none;
  }
}

@media (max-width: 420px) {
  .toolbar__zoom {
    display: none;
  }
}