/* ============================================
   读什么书 - AI好书推荐
   温暖文学风配色系统
   ============================================ */

/* Reset & Base */
*,*::before,*::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  /* Color Palette - Warm Literary */
  --bg: #F5F1E8;
  --bg-alt: #EDE7D8;
  --surface: #FFFFFF;
  --primary: #2D2517;
  --primary-light: #5C5044;
  --accent: #B8860B;
  --accent-dark: #946D0B;
  --accent-light: #D4A537;
  --muted: #9B9089;
  --border: #E5DDD0;
  --border-light: #F0EAE0;
  --shadow: rgba(45,37,23,0.08);
  --shadow-lg: rgba(45,37,23,0.15);

  /* Typography */
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;

  /* Layout */
  --content-width: 800px;
  --grid-width: 960px;
  --radius: 14px;
  --radius-sm: 8px;
  --transition: 0.3s ease;
}

html { font-size: 16px; -webkit-font-smoothing: antialiased; }

body {
  font-family: var(--font-serif);
  background: var(--bg);
  color: var(--primary);
  line-height: 1.8;
  min-height: 100vh;
}

a { color: var(--accent-dark); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent); }

img { max-width: 100%; display: block; }

/* ============================================
   Header
   ============================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 4px var(--shadow);
}

.site-header-inner {
  max-width: var(--grid-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--primary) !important;
}

.logo-icon {
  width: 38px;
  height: 38px;
  background: linear-gradient(135deg, var(--accent), var(--accent-dark));
  color: #fff;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.15rem;
  font-weight: 700;
  font-family: var(--font-serif);
  flex-shrink: 0;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.logo-text > span:first-child {
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--primary);
}

.logo-sub {
  font-size: 0.7rem;
  color: var(--muted);
  font-family: var(--font-sans);
  letter-spacing: 0.5px;
}

.site-nav {
  display: flex;
  gap: 28px;
}

.site-nav a {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  color: var(--primary-light);
  position: relative;
}

.site-nav a::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width var(--transition);
}

.site-nav a:hover { color: var(--accent-dark); }
.site-nav a:hover::after { width: 100%; }

/* ============================================
   AI Search Bar & Suggestions (inside book-section)
   ============================================ */
.book-section .ask-bar {
  max-width: 680px;
  margin: 0 auto 14px;
}

.book-section .ask-suggestions {
  margin-bottom: 20px;
}

.ask-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 4px 4px 4px 20px;
  box-shadow: 0 2px 16px var(--shadow);
  transition: border-color var(--transition);
}

.ask-bar:focus-within { border-color: var(--accent); }

.ask-input {
  flex: 1;
  border: none;
  background: transparent;
  padding: 12px 0;
  font-size: 0.95rem;
  font-family: var(--font-sans);
  color: var(--primary);
  outline: none;
}

.ask-input::placeholder { color: var(--muted); }

.ask-send-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
  transition: background var(--transition), opacity var(--transition);
}

.ask-send-btn:hover:not(:disabled) { background: var(--accent-dark); }
.ask-send-btn:disabled { background: var(--border); opacity: 0.4; cursor: not-allowed; }

.ask-suggestions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-top: 14px;
}

.ask-suggestion {
  font-size: 0.8rem;
  color: var(--primary-light);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  padding: 4px 14px;
  border-radius: 16px;
  cursor: pointer;
  transition: all var(--transition);
  font-family: var(--font-sans);
  user-select: none;
}

.ask-suggestion:hover {
  border-color: var(--accent);
  color: var(--accent-dark);
  background: rgba(184, 134, 11, 0.06);
}

/* Chat Modal Overlay */
.chat-modal-overlay {
  display: none;
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(45, 37, 23, 0.45);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.chat-modal-overlay.show {
  display: flex;
}

.chat-modal {
  width: 100%;
  max-width: 640px;
  max-height: 80vh;
  background: var(--bg);
  border-radius: var(--radius);
  box-shadow: 0 12px 48px rgba(0, 0, 0, 0.2);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  animation: modalIn 0.25s ease;
}

@keyframes modalIn {
  from { opacity: 0; transform: scale(0.96) translateY(10px); }
  to { opacity: 1; transform: scale(1) translateY(0); }
}

.chat-modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.chat-modal-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--primary);
  font-family: var(--font-sans);
}

.chat-modal-close {
  background: none;
  border: none;
  font-size: 1.4rem;
  color: var(--muted);
  cursor: pointer;
  line-height: 1;
  padding: 0;
  transition: color var(--transition);
}

.chat-modal-close:hover { color: var(--accent); }

.chat-modal-footer {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  background: var(--surface);
  border-top: 1px solid var(--border);
  flex-shrink: 0;
}

.chat-modal-footer .chat-input {
  flex: 1;
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 10px 18px;
  font-size: 0.9rem;
  font-family: var(--font-sans);
  color: var(--primary);
  background: var(--bg);
  outline: none;
  transition: border-color var(--transition);
}

.chat-modal-footer .chat-input:focus { border-color: var(--accent); }

.chat-modal-footer .chat-send-btn {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
  transition: background var(--transition), opacity var(--transition);
}

.chat-modal-footer .chat-send-btn:hover:not(:disabled) { background: var(--accent-dark); }
.chat-modal-footer .chat-send-btn:disabled { background: var(--border); opacity: 0.4; cursor: not-allowed; }

/* Chat Messages (inside modal) */
.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 20px 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  scroll-behavior: smooth;
}

.chat-messages::-webkit-scrollbar { width: 6px; }
.chat-messages::-webkit-scrollbar-track { background: var(--border-light); }
.chat-messages::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

.chat-message {
  display: flex;
  gap: 10px;
  max-width: 88%;
  animation: fadeInUp 0.3s ease;
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.chat-message.user {
  align-self: flex-end;
  flex-direction: row-reverse;
}

.chat-message.ai { align-self: flex-start; }

.msg-avatar {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.72rem;
  font-weight: 700;
  flex-shrink: 0;
  font-family: var(--font-sans);
}

.chat-message.ai .msg-avatar {
  background: var(--accent);
  color: #fff;
}

.chat-message.user .msg-avatar {
  background: var(--primary);
  color: #fff;
}

.message-content {
  background: var(--bg-alt);
  padding: 10px 16px;
  border-radius: 12px;
  font-size: 0.92rem;
  line-height: 1.75;
  color: var(--primary);
  word-break: break-word;
}

.chat-message.user .message-content {
  background: var(--primary);
  color: #fff;
}

.message-content p { margin: 0 0 8px; }
.message-content p:last-child { margin-bottom: 0; }
.message-content strong { color: var(--accent-dark); }
.chat-message.user .message-content strong { color: var(--accent-light); }

/* Chat Input & Send Button (used in modal footer) */
.chat-input {
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 10px 18px;
  font-size: 0.9rem;
  font-family: var(--font-sans);
  color: var(--primary);
  background: var(--bg);
  outline: none;
  transition: border-color var(--transition);
}

.chat-input:focus { border-color: var(--accent); }
.chat-input::placeholder { color: var(--muted); }

.chat-send-btn {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background var(--transition), opacity var(--transition);
  flex-shrink: 0;
}

.chat-send-btn:hover:not(:disabled) { background: var(--accent-dark); }
.chat-send-btn:disabled { background: var(--border); opacity: 0.4; cursor: not-allowed; }

/* Typing Indicator */
.typing-indicator {
  display: flex;
  gap: 5px;
  padding: 8px 4px;
}

.typing-indicator span {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--muted);
  animation: typing 1.4s infinite;
}

.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }

@keyframes typing {
  0%, 60%, 100% { opacity: 0.3; transform: translateY(0); }
  30% { opacity: 1; transform: translateY(-5px); }
}

/* Book Recommendation Cards in Chat */
.rec-section-title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  margin: 4px 0 6px !important;
  font-family: var(--font-sans);
}

.rec-card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  margin: 8px 0;
  transition: all var(--transition);
  cursor: pointer;
}

.rec-card:hover {
  border-color: var(--accent);
  box-shadow: 0 2px 8px var(--shadow);
}

.rec-main-link {
  display: block;
  text-decoration: none;
  color: var(--primary) !important;
}

.rec-card.ext {
  cursor: default;
  background: var(--bg-alt);
}

.rec-card.ext:hover {
  border-color: var(--border);
  box-shadow: none;
}

.rec-title {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 2px;
}

.rec-author {
  font-size: 0.8rem;
  color: var(--muted);
  font-family: var(--font-sans);
}

.rec-reason {
  font-size: 0.82rem;
  color: var(--primary-light);
  line-height: 1.6;
  margin-top: 6px;
}

.rec-badge {
  display: inline-block;
  font-size: 0.7rem;
  background: rgba(184,134,11,0.12);
  color: var(--accent-dark);
  padding: 2px 8px;
  border-radius: 4px;
  margin-top: 6px;
  font-family: var(--font-sans);
}

/* ============================================
   Book Grid Section
   ============================================ */
.book-section {
  max-width: var(--grid-width);
  margin: 0 auto;
  padding: 32px 24px;
}

.section-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
  text-align: center;
}

.section-subtitle {
  font-size: 0.85rem;
  color: var(--muted);
  text-align: center;
  margin-bottom: 24px;
  font-family: var(--font-sans);
}

.filter-bar {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 28px;
}

.filter-btn {
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 5px 16px;
  font-size: 0.82rem;
  color: var(--primary-light);
  cursor: pointer;
  transition: all var(--transition);
  font-family: var(--font-sans);
}

.filter-btn:hover {
  border-color: var(--accent);
  color: var(--accent-dark);
}

.filter-btn.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.book-card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all var(--transition);
  color: var(--primary) !important;
}

.book-card:hover {
  border-color: var(--accent);
  box-shadow: 0 4px 20px var(--shadow-lg);
  transform: translateY(-2px);
}

.book-card-top {
  padding: 20px 20px 12px;
  border-bottom: 1px solid var(--border-light);
  position: relative;
}

.card-num {
  font-size: 0.7rem;
  color: var(--accent);
  font-family: var(--font-sans);
  font-weight: 600;
  letter-spacing: 1px;
}

.card-category {
  display: block;
  font-size: 0.72rem;
  color: var(--muted);
  font-family: var(--font-sans);
  margin: 2px 0 8px;
}

.card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
  line-height: 1.4;
}

.card-author {
  font-size: 0.85rem;
  color: var(--primary-light);
  font-family: var(--font-sans);
}

.card-rating {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  margin-top: 6px;
  font-family: var(--font-sans);
}
.card-rating .star { color: var(--accent); font-size: 0.9rem; }
.card-rating .score { font-size: 0.82rem; color: var(--accent-dark); font-weight: 600; }

.card-sources {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-top: 6px;
}
.card-source-tag {
  font-size: 0.65rem;
  color: var(--muted);
  background: var(--bg-alt);
  padding: 1px 6px;
  border-radius: 3px;
  font-family: var(--font-sans);
  white-space: nowrap;
}

.author-year { color: var(--muted); }

.card-brief {
  padding: 12px 20px;
  font-size: 0.85rem;
  color: var(--primary-light);
  line-height: 1.7;
  flex: 1;
}

.book-card-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 20px;
  border-top: 1px solid var(--border-light);
}

.card-date {
  font-size: 0.75rem;
  color: var(--muted);
  font-family: var(--font-sans);
}

.card-link {
  font-size: 0.82rem;
  color: var(--accent-dark);
  font-family: var(--font-sans);
  font-weight: 500;
}

.arrow { transition: transform var(--transition); }
.book-card:hover .arrow { transform: translateX(4px); }

/* Card Badge (已解读 / 待解读) */
.card-badge {
  display: inline-block;
  font-size: 0.68rem;
  padding: 2px 8px;
  border-radius: 10px;
  font-family: var(--font-sans);
  font-weight: 500;
  letter-spacing: 0.5px;
}
.card-badge.reviewed {
  background: var(--accent);
  color: #fff;
}
.card-badge.pending {
  background: var(--bg-alt);
  color: var(--muted);
  border: 1px solid var(--border-light);
}

/* Reviewed cards: subtle accent */
.book-card.reviewed {
  border-color: var(--accent);
}

/* ============================================
   About Section
   ============================================ */
.about-section {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 40px 24px;
}

.about-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 36px;
}

.about-heading {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 16px;
  text-align: center;
}

.about-card p {
  font-size: 0.92rem;
  color: var(--primary-light);
  margin-bottom: 12px;
  line-height: 1.8;
}

.about-card ul {
  list-style: none;
  margin: 12px 0;
}

.about-card li {
  font-size: 0.9rem;
  color: var(--primary-light);
  margin-bottom: 8px;
  padding-left: 20px;
  position: relative;
}

.about-card li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 12px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

.about-card strong { color: var(--primary); }

/* ============================================
   Article Page Styles
   ============================================ */
.article-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 40px 0 32px;
}

.article-header-inner {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 0 24px;
}

.breadcrumb {
  font-size: 0.82rem;
  font-family: var(--font-sans);
  color: var(--muted);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.breadcrumb a { color: var(--accent-dark); }
.breadcrumb .sep { color: var(--border); }

.article-num {
  font-size: 0.78rem;
  color: var(--accent);
  font-family: var(--font-sans);
  font-weight: 600;
  letter-spacing: 1px;
  margin-bottom: 6px;
}

.article-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
  line-height: 1.3;
}

.article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  font-size: 0.85rem;
  color: var(--primary-light);
  font-family: var(--font-sans);
}

.meta-label { color: var(--muted); }

/* Book Cover */
.book-cover {
  width: 180px;
  margin: 28px auto 0;
  aspect-ratio: 3/4;
  background: linear-gradient(145deg, var(--primary), #1a1409);
  border-radius: 4px 8px 8px 4px;
  box-shadow: 4px 4px 16px rgba(0,0,0,0.25), inset 4px 0 0 rgba(184,134,11,0.15);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px 16px;
  text-align: center;
}

.book-cover-title {
  font-size: 1.15rem;
  font-weight: 700;
  font-family: var(--font-serif);
  line-height: 1.4;
  color: var(--bg);
}

.book-cover-line {
  width: 36px;
  height: 2px;
  background: var(--accent);
  margin: 12px 0;
}

.book-cover-author {
  font-size: 0.82rem;
  color: rgba(245, 241, 232, 0.6);
  font-family: var(--font-sans);
}

/* Article Disclaimer */
.article-disclaimer {
  margin-top: 32px;
  padding: 16px 20px;
  background: rgba(184, 134, 11, 0.06);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
}

.article-disclaimer p {
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.6;
  font-family: var(--font-sans);
}

.article-body {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 32px 24px 48px;
}

.content-section { margin-bottom: 8px; }

.section-heading {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.section-icon {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  font-weight: 700;
  font-family: var(--font-sans);
  flex-shrink: 0;
  color: #fff;
}

.section-icon.reason { background: #8B6914; }
.section-icon.insight { background: #6B8E5E; }
.section-icon.critique { background: #8B4D3E; }

.section-heading h2 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary);
}

.content-text {
  font-size: 0.95rem;
  color: var(--primary-light);
  line-height: 2;
  margin-bottom: 20px;
}

.content-text p { margin-bottom: 12px; }
.content-text strong { color: var(--primary); font-weight: 600; }

.content-text ul {
  margin: 8px 0 12px 20px;
}

.content-text li {
  margin-bottom: 6px;
  list-style: disc;
}

.content-text li::marker { color: var(--accent); }

.section-divider {
  border: none;
  border-top: 1px solid var(--border-light);
  margin: 28px 0;
}

/* Article Navigation */
.article-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 40px;
  padding-top: 28px;
  border-top: 1px solid var(--border-light);
}

.nav-link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 12px 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
  max-width: 45%;
}

.nav-link:hover {
  border-color: var(--accent);
  background: rgba(184,134,11,0.04);
}

.nav-link.next { text-align: right; margin-left: auto; }

.nav-dir {
  font-size: 0.75rem;
  color: var(--muted);
  font-family: var(--font-sans);
}

.nav-title {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--accent-dark);
}

/* ============================================
   Footer
   ============================================ */
.site-footer {
  background: var(--primary);
  color: rgba(255,255,255,0.7);
  text-align: center;
  padding: 36px 24px;
  margin-top: 40px;
}

.footer-tag {
  font-size: 0.95rem;
  font-weight: 600;
  color: rgba(255,255,255,0.9);
  margin-bottom: 4px;
}

.site-footer p {
  font-size: 0.82rem;
  font-family: var(--font-sans);
}

.footer-copyright {
  margin-top: 12px !important;
  font-size: 0.78rem !important;
  color: rgba(255,255,255,0.4) !important;
}

/* ============================================
   Buy Button & Ad Slot (Business Models)
   ============================================ */

.buy-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 5px 14px;
  font-size: 0.8rem;
  font-family: var(--font-sans);
  font-weight: 500;
  color: #fff;
  background: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 16px;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  text-decoration: none;
  white-space: nowrap;
  line-height: 1.5;
}

.buy-btn:hover {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 2px 8px rgba(184,134,11,0.3);
}

.buy-btn:active { transform: translateY(0); }

.buy-btn svg { width: 13px; height: 13px; flex-shrink: 0; }

.buy-btn.alt {
  background: #D4A537;
  border-color: #D4A537;
}
.buy-btn.alt:hover {
  background: #B8901C;
  border-color: #B8901C;
}

.buy-btn-group {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.book-info .details .buy-btn-group { margin-top: 12px; }

.book-card-bottom .buy-btn {
  padding: 3px 10px;
  font-size: 0.72rem;
}

.rec-card .buy-btn-group {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--border-light);
}

.rec-card .buy-btn { padding: 3px 10px; font-size: 0.72rem; }

.ad-slot {
  max-width: var(--content-width);
  margin: 24px auto;
  padding: 20px;
  background: var(--bg-alt);
  border: 1px dashed var(--border);
  border-radius: var(--radius-sm);
  text-align: center;
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-slot::before {
  content: "广告位";
  font-size: 0.8rem;
  color: var(--muted);
  font-family: var(--font-sans);
  letter-spacing: 1px;
}

.ad-slot.home {
  max-width: var(--grid-width);
  min-height: 100px;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 900px) {
  .book-grid { grid-template-columns: repeat(2, 1fr); }
  .article-title { font-size: 1.7rem; }
}

@media (max-width: 640px) {
  .site-header-inner { padding: 0 16px; height: 54px; }
  .site-nav { gap: 16px; }
  .site-nav a { font-size: 0.8rem; }
  .logo-text > span:first-child { font-size: 1rem; }
  .logo-sub { font-size: 0.65rem; }

  .chat-messages { padding: 12px 16px; }
  .chat-modal { max-height: 88vh; border-radius: 10px; }

  .book-section { padding: 24px 16px; }
  .book-grid { grid-template-columns: 1fr; }

  .article-header { padding: 28px 0 24px; }
  .article-header-inner { padding: 0 16px; }
  .article-title { font-size: 1.4rem; }
  .article-body { padding: 24px 16px 36px; }
  .article-meta { gap: 12px; font-size: 0.8rem; }

  .about-section { padding: 28px 16px; }
  .about-card { padding: 24px 20px; }

  .article-nav { flex-direction: column; gap: 10px; }
  .nav-link { max-width: 100%; }
  .nav-link.next { text-align: left; margin-left: 0; }
}

@media (max-width: 420px) {
  .chat-input { font-size: 0.88rem; }
}