*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --gold:          #f0c05a;
  --gold-dim:      rgba(240,192,90,0.12);
  --gold-border:   rgba(240,192,90,0.4);
  --bg:            #ffffff;
  --bg-card:       #f7f6f3;
  --bg-hover:      #f0efeb;
  --text:          #1a1a1a;
  --text-muted:    #555550;
  --text-dim:      #b0afa9;
  --border:        rgba(0,0,0,0.09);
  --border-strong: rgba(0,0,0,0.16);
  --black:         #1a1a1a;
  --t:             0.2s ease;
  --header-h:      62px;
  --sidebar-l-w:   256px;
  --sidebar-r-w:   164px;
  --pagebar-h:     56px;
}

html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Montserrat', sans-serif;
  font-size: 13px;
  line-height: 1.6;
  height: 100vh;
  overflow: hidden;
}

/* ── HEADER ──────────────────────────────────────────────── */
header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px 0 12px;
  height: var(--header-h);
  border-bottom: 1px solid var(--border);
  background: rgba(255,255,255,0.97);
  backdrop-filter: blur(12px);
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 200;
  gap: 16px;
}

.header-left,
.header-right {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.logo {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 24px;
  letter-spacing: 0.18em;
  color: var(--gold);
}
.logo span {
  color: var(--text-dim);
  font-size: 9px;
  font-family: 'Montserrat', sans-serif;
  letter-spacing: 0.22em;
  font-weight: 600;
  text-transform: uppercase;
  margin-left: 12px;
  vertical-align: middle;
}

.product-title-bar {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  text-transform: uppercase;
  flex: 1;
  text-align: center;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

/* Sidebar toggle icon buttons */
.btn-icon {
  width: 34px;
  height: 34px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 7px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-dim);
  cursor: pointer;
  transition: all var(--t);
  flex-shrink: 0;
}
.btn-icon:hover { border-color: var(--gold); color: var(--gold); }
.btn-icon.active { background: var(--gold-dim); border-color: var(--gold-border); color: var(--gold); }

/* Zoom controls */
.zoom-controls { display: flex; align-items: center; gap: 4px; }

.btn-ghost {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 7px 14px;
  border-radius: 6px;
  font-family: 'Montserrat', sans-serif;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  cursor: pointer;
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
  transition: all var(--t);
}
.btn-ghost:hover { border-color: var(--gold); color: var(--gold); }

.btn-zoom { width: 30px; height: 30px; padding: 0; border-radius: 6px; }

.zoom-label {
  min-width: 52px;
  height: 30px;
  padding: 0 8px;
  border-radius: 6px;
  font-family: 'Montserrat', sans-serif;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  background: var(--bg-card);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all var(--t);
  text-align: center;
}
.zoom-label:hover { border-color: var(--gold); color: var(--gold); }

/* ── LAYOUT ──────────────────────────────────────────────── */
.app-shell {
  display: flex;
  height: calc(100vh - var(--header-h));
  margin-top: var(--header-h);
}

/* ── SIDEBARS (shared) ───────────────────────────────────── */
.sidebar {
  flex-shrink: 0;
  background: var(--bg-card);
  overflow: hidden;
  transition: width var(--t);
  position: relative;
}

.sidebar-inner {
  overflow-y: auto;
  overflow-x: hidden;
  height: 100%;
  width: var(--sidebar-l-w); /* keeps inner width stable during collapse */
}

.sidebar-left {
  width: var(--sidebar-l-w);
  border-right: 1px solid var(--border);
}
.sidebar-left .sidebar-inner { width: var(--sidebar-l-w); }

.sidebar-right {
  width: var(--sidebar-r-w);
  border-left: 1px solid var(--border);
}
.sidebar-right .sidebar-inner { width: var(--sidebar-r-w); }

/* Collapsed state */
.sidebar-left.collapsed  { width: 0; border-right-color: transparent; }
.sidebar-right.collapsed { width: 0; border-left-color: transparent; }

.sidebar-inner::-webkit-scrollbar { width: 4px; }
.sidebar-inner::-webkit-scrollbar-track { background: transparent; }
.sidebar-inner::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 2px; }

.sidebar-section { padding: 22px 0 8px; }

.sidebar-title {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--text-dim);
  padding: 0 18px 12px;
}

.sidebar-divider {
  height: 1px;
  background: var(--border);
  margin: 8px 18px;
}

/* ── LEFT SIDEBAR ITEMS ──────────────────────────────────── */
.part-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 18px;
  cursor: pointer;
  transition: all var(--t);
  border-left: 2px solid transparent;
  user-select: none;
  white-space: nowrap;
}
.part-item:hover { background: var(--bg-hover); border-left-color: var(--gold-border); }
.part-item.active { background: var(--gold-dim); border-left-color: var(--gold); }

.part-label {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 14px;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  min-width: 48px;
  flex-shrink: 0;
  transition: color var(--t);
}
.part-item.active .part-label { color: var(--gold); }

.part-title {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  line-height: 1.4;
  transition: color var(--t);
  overflow: hidden;
  text-overflow: ellipsis;
}
.part-item.active .part-title { color: var(--black); font-weight: 600; }

/* TOC items */
.toc-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 7px 18px;
  cursor: pointer;
  transition: all var(--t);
  border-left: 2px solid transparent;
  user-select: none;
}
.toc-item:hover { background: var(--bg-hover); border-left-color: var(--gold-border); }
.toc-item.active { background: var(--gold-dim); border-left-color: var(--gold); }
.toc-item.level-1 { padding-left: 30px; }
.toc-item.level-2 { padding-left: 42px; }

.toc-page {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 13px;
  letter-spacing: 0.05em;
  color: var(--text-dim);
  min-width: 22px;
  flex-shrink: 0;
  padding-top: 1px;
  transition: color var(--t);
}
.toc-item.active .toc-page { color: var(--gold); }

.toc-title {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  line-height: 1.4;
  transition: color var(--t);
}
.toc-item.active .toc-title { color: var(--black); font-weight: 600; }
.toc-item.level-1 .toc-title { font-size: 10.5px; font-weight: 400; }
.toc-item.level-2 .toc-title { font-size: 10px; font-weight: 400; color: var(--text-dim); }

/* ── RIGHT SIDEBAR — PAGE THUMBNAILS ─────────────────────── */
.pages-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 0 12px 20px;
}

.thumb-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 5px;
  cursor: pointer;
  transition: all var(--t);
  padding: 6px;
  border-radius: 6px;
  border: 1.5px solid transparent;
}
.thumb-item:hover { background: var(--bg-hover); border-color: var(--gold-border); }
.thumb-item.active { border-color: var(--gold); background: var(--gold-dim); }

.thumb-canvas {
  display: block;
  width: 100%;
  border-radius: 2px;
  box-shadow: 0 1px 6px rgba(0,0,0,0.10);
  background: #fff;
  /* placeholder height before render */
  min-height: 80px;
}

.thumb-label {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--text-dim);
  transition: color var(--t);
}
.thumb-item.active .thumb-label { color: var(--gold); }

/* ── MAIN CONTENT ────────────────────────────────────────── */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  overflow: hidden;
}

#canvas-container {
  flex: 1;
  overflow-y: auto;
  overflow-x: auto;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 28px 24px 12px;
  position: relative;
}
#canvas-container::-webkit-scrollbar { width: 6px; height: 6px; }
#canvas-container::-webkit-scrollbar-track { background: transparent; }
#canvas-container::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 3px; }

#canvas-wrap { display: flex; justify-content: center; }

#pdf-canvas {
  display: block;
  box-shadow: 0 2px 24px rgba(0,0,0,0.10), 0 1px 4px rgba(0,0,0,0.06);
  border-radius: 2px;
  user-select: none;
  -webkit-user-select: none;
  pointer-events: none;
}

/* Loading / error */
.loading-state {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: var(--bg);
}
.loading-ring {
  width: 36px; height: 36px;
  border: 3px solid var(--border);
  border-top-color: var(--gold);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text {
  font-size: 11px; font-weight: 600;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--text-dim);
}
.error-state {
  display: flex; flex-direction: column;
  align-items: center; gap: 12px;
  padding: 40px; text-align: center;
  width: 100%;
}
.error-icon { font-size: 32px; opacity: 0.4; }
.error-title { font-size: 13px; font-weight: 700; }
.error-msg { font-size: 11px; color: var(--text-dim); max-width: 320px; line-height: 1.6; }

/* ── PAGE BAR ────────────────────────────────────────────── */
.page-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  height: var(--pagebar-h);
  border-top: 1px solid var(--border);
  background: var(--bg);
  flex-shrink: 0;
}
.page-btn {
  width: 32px; height: 32px;
  border-radius: 6px;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: all var(--t);
}
.page-btn:hover:not(:disabled) { border-color: var(--gold); color: var(--gold); }
.page-btn:disabled { opacity: 0.3; cursor: default; }

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

.page-input {
  width: 48px; height: 32px;
  border: 1px solid var(--border); border-radius: 6px;
  font-family: 'Montserrat', sans-serif;
  font-size: 12px; font-weight: 600;
  text-align: center;
  color: var(--text); background: var(--bg-card);
  outline: none;
  transition: border-color var(--t);
  -moz-appearance: textfield;
}
.page-input::-webkit-outer-spin-button,
.page-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.page-input:focus { border-color: var(--gold); }

.page-total { font-size: 12px; font-weight: 500; color: var(--text-dim); white-space: nowrap; }

/* ── RESPONSIVE ──────────────────────────────────────────────── */
@media (max-width: 768px) {
  :root { --header-h: 54px; }

  /* Header — keep logo + toggle buttons, drop everything else */
  .logo span         { display: none; }
  .product-title-bar { display: none; }
  .zoom-controls     { display: none; }
  header             { padding: 0 12px; gap: 8px; }

  /* Sidebars become fixed overlays that slide in from each edge */
  .sidebar {
    position: fixed;
    top: var(--header-h);
    bottom: 0;
    z-index: 300;
    transition: transform var(--t);
  }

  .sidebar-left {
    left: 0;
    width: var(--sidebar-l-w) !important;
    border-right: 1px solid var(--border);
    transform: translateX(0);
  }
  .sidebar-left.collapsed {
    width: var(--sidebar-l-w) !important;
    border-right-color: var(--border);
    transform: translateX(-100%);
  }

  .sidebar-right {
    right: 0;
    width: var(--sidebar-r-w) !important;
    border-left: 1px solid var(--border);
    transform: translateX(0);
  }
  .sidebar-right.collapsed {
    width: var(--sidebar-r-w) !important;
    border-left-color: var(--border);
    transform: translateX(100%);
  }

  /* Dim backdrop shown behind an open sidebar */
  #sidebar-backdrop {
    display: none;
    position: fixed;
    inset: var(--header-h) 0 0 0;
    background: rgba(0,0,0,0.35);
    z-index: 299;
    cursor: pointer;
  }
  #sidebar-backdrop.visible { display: block; }

  /* Canvas fills full width — sidebars no longer push it */
  #canvas-container { padding: 16px 8px 8px; }

  /* Larger touch targets in page bar */
  .page-bar   { height: 60px; gap: 16px; }
  .page-btn   { width: 44px; height: 44px; }
  .page-input { width: 54px; height: 38px; font-size: 13px; }
  .page-total { font-size: 13px; }
}

/* Gate card on small phones */
@media (max-width: 480px) {
  .gate-card  { padding: 36px 20px; }
  .gate-input { font-size: 12px; }
}