/* ============================================================
   红楼书屋 · 古籍典藏 — Design System
   Classical Chinese red-and-gold aesthetic
   ============================================================ */

:root {
  --color-red: #7A1020;
  --color-red-light: #8A1A2A;
  --color-red-dark: #5C0A14;
  --color-gold: #D4A94E;
  --color-gold-light: #E0BF6A;
  --color-gold-dark: #B8942A;
  --color-cream: #FDF8F0;
  --color-text: rgba(253,248,240,0.90);
  --color-text-muted: rgba(253,248,240,0.55);
  --color-border: rgba(212,169,78,0.18);
  --color-bg-card: rgba(253,248,240,0.05);

  --font-cn: 'Noto Serif SC', 'Source Han Serif SC', 'SimSun', 'STSong', serif;

  --max-width: 1400px;
  --sidebar-width: 240px;
  --nav-height: 64px;
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 4rem;
  --spacing-xl: 6rem;

  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html { scroll-behavior: smooth; font-size: 15px; }

body {
  font-family: var(--font-cn);
  color: var(--color-text);
  background: var(--color-red-dark);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

a { color: var(--color-gold); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-gold-light); }

.container { width: 100%; max-width: var(--max-width); margin: 0 auto; padding: 0 var(--spacing-md); }

/* ---- Navigation ---- */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--nav-height);
  background: rgba(92, 10, 20, 0.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}
.nav-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 100%; max-width: var(--max-width); margin: 0 auto; padding: 0 var(--spacing-md);
}
.nav-logo {
  display: flex; align-items: center; gap: 0.5rem;
  color: var(--color-gold); font-weight: 600; font-size: 1.15rem;
  letter-spacing: 0.06em;
}
.logo-icon { font-size: 1.3rem; }

.nav-links { display: flex; align-items: center; gap: var(--spacing-md); list-style: none; }
.nav-links a {
  color: var(--color-text-muted); font-size: 0.9rem; letter-spacing: 0.04em;
  padding: 0.4rem 0; position: relative; cursor: pointer;
  transition: color var(--transition);
}
.nav-links a::after {
  content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 1px;
  background: var(--color-gold); transition: width var(--transition);
}
.nav-links a:hover, .nav-links a.active { color: var(--color-gold); }
.nav-links a:hover::after, .nav-links a.active::after { width: 100%; }

.nav-toggle {
  display: none; flex-direction: column; gap: 5px;
  cursor: pointer; background: none; border: none; padding: 4px;
}
.nav-toggle span {
  display: block; width: 24px; height: 1.5px; background: var(--color-gold);
  transition: transform var(--transition), opacity var(--transition);
}

/* ---- Search ---- */
.search-item { padding: 0; }
.search-input {
  background: rgba(253,248,240,0.08);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  color: var(--color-text);
  font-family: var(--font-cn);
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
  width: 180px;
  outline: none;
  transition: border-color var(--transition), background var(--transition);
}
.search-input:focus {
  border-color: var(--color-gold);
  background: rgba(253,248,240,0.12);
}
.search-input::placeholder { color: var(--color-text-muted); font-size: 0.82rem; }


/* ---- Hero ---- */
.hero {
  padding: calc(var(--nav-height) + var(--spacing-xl)) 0 var(--spacing-lg);
  text-align: center;
  background: linear-gradient(180deg, var(--color-red-dark) 0%, var(--color-red) 60%, var(--color-red-light) 100%);
  position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; inset: 0;
  background:
    radial-gradient(ellipse at 80% 20%, rgba(212,169,78,0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 20% 80%, rgba(212,169,78,0.05) 0%, transparent 50%);
  pointer-events: none;
}
.hero-content { position: relative; z-index: 1; }

.hero-seal {
  width: 88px; height: 88px; margin: 0 auto var(--spacing-md);
  border: 2px solid var(--color-gold); border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
}
.seal-inner {
  width: 72px; height: 72px; border-radius: 50%;
  border: 1px solid rgba(212,169,78,0.35);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  color: var(--color-gold); font-size: 1.2rem; letter-spacing: 0.1em;
  font-weight: 600; line-height: 1.3;
}

.hero h1 {
  font-size: clamp(2.4rem, 4vw, 3.2rem);
  color: var(--color-gold); letter-spacing: 0.12em; font-weight: 600;
  margin-bottom: var(--spacing-xs);
}
.hero-subtitle {
  font-size: clamp(1rem, 1.5vw, 1.2rem);
  color: var(--color-gold-light); letter-spacing: 0.08em;
  margin-bottom: var(--spacing-sm);
}
.hero-desc {
  color: var(--color-text-muted); font-size: 0.95rem; line-height: 1.8;
}

/* ---- Library Layout ---- */
.library-section {
  padding: var(--spacing-lg) 0;
  min-height: 60vh;
  background: linear-gradient(180deg, var(--color-red) 0%, var(--color-red-dark) 100%);
}
.library-layout {
  display: flex; gap: var(--spacing-lg);
  align-items: flex-start;
}

/* ---- Sidebar ---- */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  position: sticky; top: calc(var(--nav-height) + var(--spacing-md));
  max-height: calc(100vh - var(--nav-height) - var(--spacing-md) * 2);
  overflow-y: auto;
  padding-right: var(--spacing-sm);
}
.sidebar::-webkit-scrollbar { width: 3px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: 2px; }

.sidebar-title {
  font-size: 0.85rem; color: var(--color-gold);
  letter-spacing: 0.06em; margin-bottom: var(--spacing-sm);
  padding-bottom: var(--spacing-xs);
  border-bottom: 1px solid var(--color-border);
}

.category-tree { list-style: none; }
.category-tree li { margin: 0; }
.category-tree a {
  display: block; padding: 0.35rem 0.8rem;
  font-size: 0.85rem; color: var(--color-text-muted);
  border-radius: 3px; cursor: pointer;
  transition: all var(--transition);
  border-left: 2px solid transparent;
}
.category-tree a:hover {
  color: var(--color-gold-light);
  background: rgba(212,169,78,0.06);
}
.category-tree a.active {
  color: var(--color-gold);
  background: rgba(212,169,78,0.10);
  border-left-color: var(--color-gold);
  font-weight: 500;
}
.category-tree .sub-category a {
  padding-left: 1.6rem;
  font-size: 0.8rem;
}
.category-tree .sub-sub-category a {
  padding-left: 2.4rem;
  font-size: 0.78rem;
}

/* ---- Main Content ---- */
.main-content {
  flex: 1;
  min-width: 0;
}

.breadcrumb {
  display: flex; align-items: center; gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
  padding-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--color-border);
}
.current-category {
  font-size: 1.3rem; color: var(--color-gold-light);
  font-weight: 500; letter-spacing: 0.04em;
}
.book-count {
  font-size: 0.85rem; color: var(--color-text-muted);
}

.book-error {
  display: none;
  background: rgba(212,169,78,0.08);
  border: 1px solid rgba(212,169,78,0.2);
  border-radius: 4px;
  padding: var(--spacing-sm) var(--spacing-md);
  margin-bottom: var(--spacing-md);
  font-size: 0.9rem;
  color: var(--color-gold-light);
}
.book-error a { color: var(--color-gold); text-decoration: underline; }
.book-error.visible { display: block; }

/* ---- Book Grid ---- */
.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--spacing-md);
}

.book-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: var(--spacing-md);
  transition: all var(--transition);
  position: relative;
}
.book-card:hover {
  border-color: var(--color-gold);
  background: rgba(253,248,240,0.08);
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(0,0,0,0.25);
}

.book-card-header {
  display: flex; align-items: flex-start; justify-content: space-between;
  gap: var(--spacing-sm); margin-bottom: var(--spacing-xs);
}
.book-title {
  font-size: 1.1rem; font-weight: 500; color: var(--color-gold-light);
  line-height: 1.4;
}
.book-title a { color: inherit; }
.book-title a:hover { color: var(--color-gold); }

.book-authors {
  font-size: 0.82rem; color: var(--color-text-muted);
  margin-bottom: var(--spacing-xs);
  line-height: 1.6;
}
.book-author {
  display: inline-block;
}
.book-author + .book-author::before {
  content: '、';
}

.book-dynasty {
  display: inline-block;
  font-size: 0.75rem;
  padding: 0.1rem 0.5rem;
  border: 1px solid rgba(212,169,78,0.2);
  border-radius: 2px;
  color: var(--color-gold);
  margin-bottom: var(--spacing-sm);
}

.book-desc {
  font-size: 0.82rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: 0;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.book-actions {
  margin-top: var(--spacing-sm);
  display: flex; gap: var(--spacing-xs);
  flex-wrap: wrap;
}
.btn-read {
  display: inline-block;
  padding: 0.3rem 1rem;
  border: 1px solid var(--color-gold);
  color: var(--color-gold);
  font-size: 0.8rem;
  font-family: var(--font-cn);
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: all var(--transition);
  border-radius: 2px;
}
.btn-read:hover {
  background: var(--color-gold);
  color: var(--color-red-dark);
}
.btn-original {
  display: inline-block;
  padding: 0.3rem 1rem;
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 0.8rem;
  font-family: var(--font-cn);
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: all var(--transition);
  border-radius: 2px;
}
.btn-original:hover {
  border-color: var(--color-text-muted);
  color: var(--color-text);
}

/* ---- Pagination ---- */
.pagination {
  display: flex; align-items: center; justify-content: center;
  gap: 0.3rem; margin-top: var(--spacing-lg); padding: var(--spacing-md) 0;
}
.pagination button {
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--color-border);
  background: transparent;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  font-family: var(--font-cn);
  cursor: pointer;
  transition: all var(--transition);
  border-radius: 2px;
}
.pagination button:hover:not(:disabled):not(.active) {
  border-color: var(--color-gold);
  color: var(--color-gold);
}
.pagination button.active {
  background: var(--color-gold);
  border-color: var(--color-gold);
  color: var(--color-red-dark);
  font-weight: 500;
}
.pagination button:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.loading {
  text-align: center; padding: var(--spacing-xl);
  color: var(--color-text-muted); font-size: 0.95rem;
}

/* ---- Footer ---- */
.footer {
  background: #4A0812;
  color: var(--color-text-muted);
  padding: var(--spacing-lg) 0;
  font-size: 0.85rem;
  border-top: 1px solid var(--color-border);
}
.footer-inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--spacing-lg);
}
.footer h4 {
  color: var(--color-gold);
  margin-bottom: var(--spacing-sm);
  font-size: 0.9rem;
}
.footer a { color: var(--color-text-muted); }
.footer a:hover { color: var(--color-gold); }
.footer p { margin-bottom: 0.5rem; }
.footer ul { list-style: none; }
.footer li { margin-bottom: 0.3rem; }
.footer-bottom {
  margin-top: var(--spacing-md);
  padding-top: var(--spacing-md);
  border-top: 1px solid rgba(253,248,240,0.06);
  text-align: center;
  font-size: 0.78rem;
  color: rgba(253,248,240,0.25);
}

/* ---- Responsive ---- */
@media (max-width: 1024px) {
  .library-layout { flex-direction: column; }
  .sidebar {
    width: 100%; position: static;
    max-height: none; overflow-y: visible;
    margin-bottom: var(--spacing-md);
  }
  .category-tree { display: flex; flex-wrap: wrap; gap: 0.3rem; }
  .category-tree a {
    border-left: none;
    border: 1px solid var(--color-border);
    padding: 0.25rem 0.6rem;
    font-size: 0.8rem;
  }
  .category-tree a.active {
    border-left: none;
    border-color: var(--color-gold);
  }
  .category-tree .sub-category a { padding-left: 0.6rem; }
  .category-tree .sub-sub-category a { padding-left: 0.6rem; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  :root { --nav-height: 56px; }
  .nav-links {
    position: fixed; top: var(--nav-height); left: 0; right: 0; bottom: 0;
    background: rgba(92, 10, 20, 0.98); backdrop-filter: blur(16px);
    flex-direction: column; justify-content: center; gap: var(--spacing-lg);
    transform: translateX(100%); transition: transform var(--transition);
  }
  .nav-links.open { transform: translateX(0); }
  .nav-links a { font-size: 1.1rem; }
  .search-item { width: 100%; text-align: center; }
  .search-input { width: 80%; font-size: 1rem; padding: 0.6rem 1rem; }
  .nav-toggle { display: flex; }
  .book-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; }
}