:root {
  --bg: #f5f5f0;
  --text: #2c2c2c;
  --header-bg: #fff;
  --card-bg: #fff;
  --border: #e0e0e0;
  --accent: #4a7c59;
  --accent-hover: #3a6247;
  --muted: #888;
  --error: #c0392b;
  --reader-bg: #faf9f6;
  --font-size: 18px;
}

[data-theme="dark"] {
  --bg: #1a1a2e;
  --text: #e0e0e0;
  --header-bg: #16213e;
  --card-bg: #1f2b47;
  --border: #2a3a5c;
  --accent: #6dbf8b;
  --accent-hover: #5aad78;
  --muted: #8899aa;
  --error: #e74c3c;
  --reader-bg: #16213e;
}

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

body {
  font-family: 'Georgia', 'Noto Serif', serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

.screen { display: none; }
.screen.active { display: block; }

/* Login */
.login-box {
  max-width: 360px;
  margin: 20vh auto;
  padding: 2rem;
  background: var(--card-bg);
  border-radius: 12px;
  box-shadow: 0 4px 24px rgba(0,0,0,0.1);
}

.login-box h1 {
  text-align: center;
  margin-bottom: 1.5rem;
  font-size: 1.8rem;
}

.login-box input {
  width: 100%;
  padding: 12px 16px;
  margin-bottom: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  background: var(--bg);
  color: var(--text);
}

.login-box button {
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s;
}

.login-box button:hover { background: var(--accent-hover); }
.error { color: var(--error); text-align: center; margin-top: 8px; font-size: 0.9rem; }

/* Header */
header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  background: var(--header-bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

header h1 { font-size: 1.3rem; }
header h2 { font-size: 1.1rem; }

.header-right {
  display: flex;
  align-items: center;
  gap: 12px;
}

#user-name { color: var(--muted); font-size: 0.9rem; }

.btn-small {
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--card-bg);
  color: var(--text);
  cursor: pointer;
  font-size: 0.85rem;
  transition: background 0.2s;
}

.btn-small:hover { background: var(--border); }

/* Search */
.search-bar {
  padding: 12px 20px;
}

.search-bar input {
  width: 100%;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  background: var(--card-bg);
  color: var(--text);
}

/* Book Grid */
.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  padding: 12px 20px 40px;
}

.book-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
}

.book-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}

.book-card h3 {
  font-size: 1rem;
  margin-bottom: 4px;
  line-height: 1.4;
}

.book-card .author {
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 8px;
}

.book-card .meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8rem;
  color: var(--muted);
}

.book-card .progress-badge {
  background: var(--accent);
  color: #fff;
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 0.75rem;
}

/* Reader */
.reader-content {
  max-width: 700px;
  margin: 0 auto;
  padding: 24px 20px 120px;
  font-size: var(--font-size);
  line-height: 1.8;
  white-space: pre-wrap;
  background: var(--reader-bg);
  min-height: 60vh;
}

.reader-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 20px;
  background: var(--header-bg);
  border-top: 1px solid var(--border);
}

.nav-btn {
  padding: 10px 24px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s;
}

.nav-btn:hover { background: var(--accent-hover); }
.nav-btn:disabled { opacity: 0.4; cursor: not-allowed; }

#chapter-indicator {
  color: var(--muted);
  font-size: 0.9rem;
}

/* Sidebar TOC */
.sidebar {
  position: fixed;
  top: 0;
  right: 0;
  width: 320px;
  max-width: 85vw;
  height: 100vh;
  background: var(--card-bg);
  border-left: 1px solid var(--border);
  z-index: 100;
  transform: translateX(100%);
  transition: transform 0.25s ease;
  overflow-y: auto;
}

.sidebar.open { transform: translateX(0); }
.sidebar.hidden { transform: translateX(100%); }

.sidebar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--card-bg);
}

.toc-list {
  padding: 8px 0;
}

.toc-item {
  padding: 10px 16px;
  cursor: pointer;
  font-size: 0.9rem;
  border-bottom: 1px solid var(--border);
  transition: background 0.15s;
}

.toc-item:hover { background: var(--bg); }
.toc-item.active { color: var(--accent); font-weight: bold; }

/* Theme Toggle */
.theme-btn {
  position: fixed;
  bottom: 70px;
  right: 20px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--card-bg);
  font-size: 1.2rem;
  cursor: pointer;
  z-index: 50;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  transition: transform 0.2s;
}

.theme-btn:hover { transform: scale(1.1); }

/* Font Controls */
.font-controls {
  position: fixed;
  bottom: 70px;
  right: 76px;
  display: flex;
  gap: 6px;
  z-index: 50;
}

.font-controls.hidden { display: none; }

.font-controls button {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--card-bg);
  font-size: 0.9rem;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

/* Loading */
.loading {
  text-align: center;
  padding: 40px;
  color: var(--muted);
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--muted);
}

/* Mobile */
@media (max-width: 600px) {
  .book-grid {
    grid-template-columns: 1fr;
  }

  header h1 { font-size: 1.1rem; }

  .reader-content {
    padding: 16px 16px 100px;
    font-size: 16px;
  }

  .nav-btn {
    padding: 8px 16px;
    font-size: 0.9rem;
  }
}