/* ===== CSS CUSTOM PROPERTIES ===== */
:root {
  --primary: #0d3b66;
  --secondary: #1a73e8;
  --accent: #f4a261;
  --bg: #f8f9ff;
  --card-bg: #ffffff;
  --text: #1a1a2e;
  --text-muted: #6b7280;
  --border: #e5e7eb;
  --success: #2ecc71;
  --controls-height: 72px;
  --sidebar-width: 280px;
  --max-content: 720px;
  --font-body: 'Inter', system-ui, sans-serif;
  --font-sinhala: 'Noto Sans Sinhala', 'Iskoola Pota', serif;
  --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --shadow-sm: 0 1px 3px rgba(0,0,0,.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,.1);
}

/* High contrast mode */
body.high-contrast {
  --bg: #000;
  --card-bg: #0a0a0a;
  --text: #fff;
  --text-muted: #e0e0e0;
  --border: #555;
  --primary: #4db8ff;
  --secondary: #7dd3fc;
}
body.high-contrast .controls-bar { background: #000; border-color: #555; }
body.high-contrast .sidebar { background: #0a0a0a; border-color: #555; }
body.high-contrast .chapter-content h2 { color: #4db8ff; }
body.high-contrast .summary-box { background: #001a2e; border-color: #4db8ff; color: #fff; }

/* Font size variants */
body.font-sm { --base-font: 15px; }
body.font-md { --base-font: 18px; }
body.font-lg { --base-font: 21px; }
body.font-xl { --base-font: 25px; }

/* ===== RESET ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

/* ===== SKIP LINK ===== */
.skip-link {
  position: fixed;
  top: -100px;
  left: 16px;
  background: var(--primary);
  color: #fff;
  padding: 12px 20px;
  border-radius: 0 0 8px 8px;
  font-weight: 600;
  font-family: var(--font-body);
  font-size: 15px;
  z-index: 9999;
  transition: top var(--transition);
  text-decoration: none;
}
.skip-link:focus { top: 0; outline: 3px solid var(--accent); outline-offset: 2px; }

/* ===== SR-ONLY ===== */
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; }

/* ===== FOCUS VISIBLE ===== */
:focus-visible { outline: 2px solid var(--secondary); outline-offset: 2px; border-radius: 2px; }

/* ===== LOADING ===== */
.loading-overlay {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  position: fixed;
  inset: 0;
  background: var(--bg);
  z-index: 1000;
  font-family: var(--font-body);
  font-size: 16px;
  color: var(--text-muted);
}
.loading-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) { .loading-spinner { animation: none; border-top-color: var(--primary); } }

/* ===== CONTROLS BAR ===== */
.controls-bar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.96);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
}
.controls-inner {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 16px;
  height: 60px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.controls-left, .controls-right { display: flex; align-items: center; gap: 4px; }
.controls-center { display: flex; align-items: center; gap: 8px; margin: 0 auto; }

/* Control buttons */
.ctrl-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-width: 44px;
  min-height: 44px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text);
  font-size: 14px;
  font-weight: 600;
  font-family: var(--font-body);
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
  flex-shrink: 0;
  text-decoration: none;
}
.ctrl-btn:hover { background: var(--bg); border-color: var(--secondary); color: var(--primary); }
.ctrl-btn:active { transform: scale(0.96); }
.ctrl-btn:focus-visible { outline: 2px solid var(--secondary); outline-offset: 2px; }
.ctrl-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

.ctrl-play {
  background: var(--success);
  color: #fff;
  border-color: var(--success);
  min-width: 130px;
  justify-content: center;
  font-size: 15px;
}
.ctrl-play:hover { background: #27ae60; border-color: #27ae60; color: #fff; }
.ctrl-play.playing { background: var(--primary); border-color: var(--primary); }
.ctrl-play.playing:hover { background: var(--primary); opacity: 0.9; }

.ctrl-home { color: var(--text-muted); }
.ctrl-label { display: none; }
@media (min-width: 768px) { .ctrl-label { display: inline; } }

.ctrl-select {
  height: 44px;
  padding: 0 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text);
  font-size: 13px;
  font-family: var(--font-body);
  font-weight: 600;
  cursor: pointer;
  min-width: 72px;
}
.ctrl-select:focus-visible { outline: 2px solid var(--secondary); }

.font-controls { display: flex; gap: 2px; }
.font-btn { min-width: 36px; padding: 0 8px; font-size: 13px; }

/* Progress bar */
.progress-track {
  height: 3px;
  background: var(--border);
}
.progress-fill {
  height: 100%;
  background: var(--secondary);
  transition: width 400ms ease;
}

/* TTS status */
.tts-status {
  text-align: center;
  font-size: 11px;
  color: var(--text-muted);
  padding: 2px 16px;
  background: var(--bg);
  border-top: 1px solid var(--border);
  min-height: 20px;
  font-family: var(--font-body);
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

/* ===== SHORTCUTS PANEL ===== */
.shortcuts-panel {
  position: fixed;
  inset: 0;
  z-index: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0.5);
  padding: 20px;
}
.shortcuts-panel[hidden] { display: none; }
.shortcuts-content {
  background: var(--card-bg);
  border-radius: 16px;
  width: 100%;
  max-width: 400px;
  box-shadow: var(--shadow-md);
  overflow: hidden;
}
.shortcuts-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  border-bottom: 1px solid var(--border);
}
.shortcuts-header h2 { font-size: 1.1rem; font-weight: 700; color: var(--primary); }
.close-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  cursor: pointer;
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  transition: all var(--transition);
}
.close-btn:hover { background: var(--bg); color: var(--text); }
.shortcuts-list { padding: 16px 24px; display: grid; gap: 12px; }
.shortcut-item { display: flex; align-items: center; justify-content: space-between; gap: 16px; font-size: 14px; }
.shortcut-item dd { color: var(--text-muted); }
kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 3px 10px;
  font-size: 13px;
  font-family: var(--font-body);
  font-weight: 600;
  color: var(--text);
  box-shadow: 0 1px 2px rgba(0,0,0,.1);
  min-width: 36px;
}

/* ===== READER LAYOUT ===== */
.reader-layout {
  display: flex;
  min-height: calc(100vh - 85px);
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  background: var(--card-bg);
  border-right: 1px solid var(--border);
  position: sticky;
  top: 85px;
  height: calc(100vh - 85px);
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition);
}
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    top: 85px;
    left: 0;
    height: calc(100vh - 85px);
    z-index: 50;
    transform: translateX(-100%);
    box-shadow: var(--shadow-md);
  }
  .sidebar.open { transform: translateX(0); }
}
.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 20px 12px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}
.sidebar-title { font-size: 13px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-muted); }
.sidebar-count { font-size: 12px; font-weight: 600; color: var(--text-muted); background: var(--bg); padding: 2px 8px; border-radius: 999px; border: 1px solid var(--border); }
.chapter-list { padding: 12px; flex: 1; }
.chapter-list li { list-style: none; }
.chapter-list button {
  width: 100%;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px;
  border-radius: 10px;
  background: none;
  border: none;
  cursor: pointer;
  text-align: left;
  font-family: var(--font-body);
  transition: background var(--transition);
  min-height: 52px;
  color: var(--text);
}
.chapter-list button:hover { background: var(--bg); }
.chapter-list button.active { background: var(--primary); color: #fff; }
.chapter-list button:focus-visible { outline: 2px solid var(--secondary); outline-offset: 1px; }
.ch-num {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
  flex-shrink: 0;
  color: var(--text);
}
.active .ch-num { background: rgba(255,255,255,0.25); color: #fff; }
.ch-info { display: flex; flex-direction: column; gap: 3px; }
.ch-title { font-size: 13px; font-weight: 600; font-family: var(--font-sinhala); line-height: 1.5; }
.ch-meta { font-size: 11px; color: var(--text-muted); font-family: var(--font-body); }
.active .ch-meta { color: rgba(255,255,255,0.7); }
.sidebar-progress { padding: 12px 20px; border-top: 1px solid var(--border); flex-shrink: 0; }
.sidebar-progress-label { font-size: 12px; color: var(--text-muted); font-family: var(--font-body); }

/* ===== MAIN CONTENT ===== */
.reader-main { flex: 1; min-width: 0; }
.reader-content-wrap { max-width: calc(var(--max-content) + 96px); margin: 0 auto; padding: 32px 24px 64px; }
@media (min-width: 1024px) { .reader-content-wrap { padding: 40px 48px 80px; } }

/* Chapter navigation (top/bottom) */
.chapter-nav-top, .chapter-nav-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}
.chapter-nav-bottom { margin-top: 40px; margin-bottom: 0; }
.nav-ch-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text-muted);
  font-size: 14px;
  font-weight: 600;
  font-family: var(--font-body);
  cursor: pointer;
  transition: all var(--transition);
  min-height: 44px;
}
.nav-ch-btn:hover:not(:disabled) { background: var(--primary); color: #fff; border-color: var(--primary); }
.nav-ch-btn:disabled { opacity: 0.4; cursor: not-allowed; }
.nav-ch-btn.next { margin-left: auto; }
.chapter-breadcrumb {
  flex: 1;
  text-align: center;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-sinhala);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ===== CHAPTER CONTENT ===== */
.chapter-content {
  font-family: var(--font-sinhala);
  font-size: var(--base-font, 18px);
  line-height: 1.9;
  color: var(--text);
  max-width: var(--max-content);
  margin: 0 auto;
}
.chapter-content:focus { outline: none; }
.chapter-content h2 {
  font-size: calc(var(--base-font, 18px) * 1.5);
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 20px;
  line-height: 1.3;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--border);
}
.chapter-content h3 {
  font-size: calc(var(--base-font, 18px) * 1.2);
  font-weight: 700;
  color: var(--primary);
  margin: 24px 0 12px;
}
.chapter-content p {
  margin-bottom: 16px;
  transition: background var(--transition);
}
.chapter-content p:focus { outline: 1px dashed var(--secondary); outline-offset: 4px; border-radius: 4px; }

/* Summary box */
.summary-box {
  background: #dbeafe;
  border-left: 4px solid var(--secondary);
  border-radius: 0 8px 8px 0;
  padding: 16px 20px;
  margin: 20px 0 24px;
  font-style: italic;
  font-family: var(--font-body);
  font-size: calc(var(--base-font, 18px) * 0.9);
  color: var(--primary);
  line-height: 1.7;
}
body.high-contrast .summary-box { background: #001a2e; color: #fff; border-color: #4db8ff; }

/* Skip link inside content */
.chapter-content .skip-link {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  font-size: 14px;
}
.chapter-content .skip-link:focus {
  position: static;
  width: auto;
  height: auto;
  clip: auto;
  white-space: normal;
  display: inline-block;
  background: var(--primary);
  color: #fff;
  padding: 6px 12px;
  border-radius: 4px;
  margin-bottom: 8px;
  text-decoration: none;
  outline: 2px solid var(--accent);
}

/* Images */
.chapter-content figure { margin: 24px 0; }
.chapter-content img.page-scan {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border);
}
.chapter-content figcaption { font-size: 13px; color: var(--text-muted); margin-top: 8px; font-family: var(--font-body); }

/* Article/section wrappers */
.chapter-content article { display: block; }
.chapter-content section { display: block; }

/* ===== RESPONSIVE 375px ===== */
@media (max-width: 480px) {
  .controls-inner { gap: 4px; padding: 0 8px; }
  .ctrl-btn { min-width: 40px; padding: 0 8px; }
  .ctrl-play { min-width: 110px; }
  .font-btn { min-width: 32px; }
  .reader-content-wrap { padding: 20px 16px 40px; }
  .chapter-nav-top, .chapter-nav-bottom { gap: 8px; }
  .chapter-breadcrumb { font-size: 12px; }
}

/* ===== DARK MODE ===== */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f0f1a;
    --card-bg: #1a1a2e;
    --text: #f0f0ff;
    --text-muted: #9ca3af;
    --border: #2d2d40;
    --shadow-sm: 0 1px 3px rgba(0,0,0,.3);
    --shadow-md: 0 4px 12px rgba(0,0,0,.3);
  }
  .controls-bar { background: rgba(15,15,26,0.96); }
  .summary-box { background: #1e3a5f; color: #dbeafe; }
}