/* ========================================
   AI博客 - 全局设计系统
   零预算 · 现代感 · 移动优先
   ======================================== */

/* ---------- CSS变量 ---------- */
:root {
  /* 主色 */
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  /* 强调色 */
  --accent: #f59e0b;
  --accent-dark: #d97706;
  /* 成功/状态 */
  --success: #10b981;
  --danger: #ef4444;
  /* 中性色 */
  --text: #1e293b;
  --text-secondary: #64748b;
  --text-light: #94a3b8;
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-card: #ffffff;
  --border: #e2e8f0;
  /* 圆角 */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  /* 阴影 */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
  /* 字体 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue",
               Helvetica, Arial, sans-serif;
  --font-mono: "Fira Code", "Source Code Pro", "Consolas", monospace;
  /* 间距 */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  /* 容器 */
  --container: 1100px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: var(--primary); text-decoration: none; transition: color .2s; }
a:hover { color: var(--primary-dark); }
ul, ol { list-style: none; }
button { cursor: pointer; font-family: inherit; }
input, textarea { font-family: inherit; font-size: inherit; }

/* ---------- 容器 ---------- */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ---------- 通用按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 22px;
  border: none;
  border-radius: var(--radius-md);
  font-size: .95rem;
  font-weight: 600;
  transition: all .25s;
  text-decoration: none;
}
.btn-primary {
  background: var(--primary);
  color: #fff;
}
.btn-primary:hover {
  background: var(--primary-dark);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}
.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
}
.btn-outline:hover {
  background: var(--primary);
  color: #fff;
}
.btn-accent {
  background: var(--accent);
  color: #fff;
}
.btn-accent:hover {
  background: var(--accent-dark);
  color: #fff;
}
.btn-sm { padding: 6px 14px; font-size: .85rem; }
.btn-lg { padding: 14px 32px; font-size: 1.05rem; }

/* ---------- 导航栏 ---------- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 var(--space-md);
}
.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.nav-logo {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
}
.nav-logo span { color: var(--primary); }
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}
.nav-links a {
  color: var(--text-secondary);
  font-size: .92rem;
  font-weight: 500;
  transition: color .2s;
  position: relative;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
}
.nav-links a.active::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--primary);
  border-radius: 1px;
}
.nav-cta { margin-left: var(--space-sm); }

/* 移动端菜单按钮 */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text);
}

/* ---------- Hero区 ---------- */
.hero {
  padding: var(--space-3xl) 0 var(--space-2xl);
  text-align: center;
  background: linear-gradient(135deg, #eff6ff 0%, #f0fdf4 50%, #fffbeb 100%);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(37,99,235,.12) 0%, transparent 70%);
  top: -100px; right: -100px;
  border-radius: 50%;
}
.hero h1 {
  font-size: clamp(1.8rem, 5vw, 2.8rem);
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: var(--space-md);
}
.hero h1 .highlight {
  background: linear-gradient(135deg, var(--primary), #7c3aed);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 580px;
  margin: 0 auto var(--space-lg);
}
.hero-buttons {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}
.hero-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-2xl);
  margin-top: var(--space-xl);
}
.hero-stats .stat { text-align: center; }
.hero-stats .stat-num {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--primary);
}
.hero-stats .stat-label {
  font-size: .85rem;
  color: var(--text-light);
}

/* ---------- 区块标题 ---------- */
.section {
  padding: var(--space-2xl) 0;
}
.section-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}
.section-header h2 {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
}
.section-header p {
  color: var(--text-secondary);
  font-size: .95rem;
}

/* ---------- 卡片通用 ---------- */
a.card { display: block; color: inherit; text-decoration: none; }
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: transform .25s, box-shadow .25s;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}
.card-img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  background: var(--bg-secondary);
}
.card-body { padding: var(--space-md); }
.card-tag {
  display: inline-block;
  padding: 2px 10px;
  font-size: .75rem;
  font-weight: 600;
  border-radius: 50px;
  background: var(--primary-light);
  color: var(--primary);
  margin-bottom: var(--space-sm);
}
.card-tag.tag-hot {
  background: #fef2f2;
  color: var(--danger);
}
.card-tag.tag-new {
  background: #ecfdf5;
  color: var(--success);
}
.card-title {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: var(--space-xs);
  line-height: 1.4;
}
.card-desc {
  font-size: .88rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.card-meta {
  font-size: .8rem;
  color: var(--text-light);
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

/* ---------- 网格布局 ---------- */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-lg); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-lg); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-md); }

/* ---------- 推荐/广告位 ---------- */
.ad-banner {
  background: linear-gradient(135deg, #eff6ff, #f0fdf4);
  border: 2px dashed var(--primary);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-align: center;
  margin: var(--space-lg) 0;
}
.ad-banner .ad-label {
  font-size: .7rem;
  color: var(--text-light);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: var(--space-xs);
}

/* ---------- 订阅框 ---------- */
.subscribe-box {
  background: linear-gradient(135deg, var(--primary), #7c3aed);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
  color: #fff;
}
.subscribe-box h3 { font-size: 1.3rem; margin-bottom: var(--space-sm); }
.subscribe-box p { opacity: .9; margin-bottom: var(--space-md); font-size: .95rem; }
.subscribe-form {
  display: flex;
  gap: var(--space-sm);
  max-width: 440px;
  margin: 0 auto;
}
.subscribe-form input {
  flex: 1;
  padding: 10px 16px;
  border: none;
  border-radius: var(--radius-md);
  font-size: .95rem;
}
.subscribe-form button {
  padding: 10px 20px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-weight: 700;
  transition: background .2s;
}
.subscribe-form button:hover { background: var(--accent-dark); }

/* ---------- 打赏区 ---------- */
.donate-section {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
}
.donate-codes {
  display: flex;
  justify-content: center;
  gap: var(--space-xl);
  margin: var(--space-lg) 0;
  flex-wrap: wrap;
}
.donate-code-item { text-align: center; }
.donate-code-item .qr-placeholder {
  width: 160px;
  height: 160px;
  background: #fff;
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-sm);
  font-size: .8rem;
  color: var(--text-light);
}

/* ---------- 对比表格 ---------- */
.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .9rem;
}
.compare-table th, .compare-table td {
  padding: 12px 16px;
  border: 1px solid var(--border);
  text-align: left;
}
.compare-table th {
  background: var(--primary);
  color: #fff;
  font-weight: 600;
}
.compare-table tr:nth-child(even) { background: var(--bg-secondary); }
.compare-table .badge-best {
  background: var(--success);
  color: #fff;
  padding: 2px 8px;
  border-radius: 50px;
  font-size: .75rem;
  font-weight: 600;
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--text);
  color: #cbd5e1;
  padding: var(--space-2xl) 0 var(--space-lg);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-xl);
  margin-bottom: var(--space-xl);
}
.footer h4 {
  color: #fff;
  font-size: .95rem;
  margin-bottom: var(--space-md);
}
.footer a {
  color: #94a3b8;
  font-size: .88rem;
  display: block;
  margin-bottom: var(--space-sm);
  transition: color .2s;
}
.footer a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid #334155;
  padding-top: var(--space-md);
  text-align: center;
  font-size: .8rem;
  color: #64748b;
}

/* ---------- 免责/披露条 ---------- */
.disclosure {
  background: #fffbeb;
  border-left: 4px solid var(--accent);
  padding: var(--space-md);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: .85rem;
  color: #92400e;
  margin: var(--space-md) 0;
}

/* ---------- 面包屑 ---------- */
.breadcrumb {
  font-size: .85rem;
  color: var(--text-light);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: 6px;
}
.breadcrumb a { color: var(--text-secondary); }

/* ---------- 文章正文样式 ---------- */
.article-content h2 {
  font-size: 1.4rem;
  font-weight: 700;
  margin: var(--space-xl) 0 var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--primary-light);
}
.article-content h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin: var(--space-lg) 0 var(--space-sm);
}
.article-content p {
  margin-bottom: var(--space-md);
  color: var(--text);
}
.article-content ul, .article-content ol {
  margin: 0 0 var(--space-md) var(--space-lg);
}
.article-content li {
  margin-bottom: var(--space-xs);
  list-style: disc;
}
.article-content ol li { list-style: decimal; }
.article-content blockquote {
  border-left: 4px solid var(--primary);
  background: var(--primary-light);
  padding: var(--space-md);
  margin: var(--space-md) 0;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.article-content code {
  background: #f1f5f9;
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: .88em;
}
.article-content pre {
  background: #1e293b;
  color: #e2e8f0;
  padding: var(--space-md);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin: var(--space-md) 0;
}
.article-content pre code {
  background: none;
  padding: 0;
  color: inherit;
}
.article-content img {
  border-radius: var(--radius-md);
  margin: var(--space-md) 0;
}
.tip-box {
  background: #ecfdf5;
  border-left: 4px solid var(--success);
  padding: var(--space-md);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: var(--space-md) 0;
}
.tip-box .tip-title {
  font-weight: 700;
  color: #065f46;
  margin-bottom: var(--space-xs);
}

/* ---------- TOC目录 ---------- */
.toc {
  position: sticky;
  top: 80px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  max-height: calc(100vh - 100px);
  overflow-y: auto;
}
.toc h4 {
  font-size: .9rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
  color: var(--text-secondary);
}
.toc a {
  display: block;
  font-size: .85rem;
  color: var(--text-secondary);
  padding: 4px 0 4px 12px;
  border-left: 2px solid transparent;
  transition: all .2s;
}
.toc a:hover, .toc a.active {
  color: var(--primary);
  border-left-color: var(--primary);
}

/* ---------- 响应式 ---------- */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .menu-toggle { display: block; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: #fff;
    padding: var(--space-md);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
    gap: var(--space-md);
  }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .hero-stats { gap: var(--space-lg); }
  .subscribe-form { flex-direction: column; }
  .article-layout { flex-direction: column; }
  .toc { position: static; max-height: none; }
}

@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
  .hero { padding: var(--space-xl) 0; }
}

/* ---------- Toast提示 ---------- */
.toast {
  position: fixed;
  bottom: 80px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: #1e293b;
  color: #fff;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  font-size: .9rem;
  font-weight: 500;
  z-index: 9999;
  opacity: 0;
  transition: opacity .3s, transform .3s;
  pointer-events: none;
  max-width: 90vw;
  text-align: center;
  box-shadow: var(--shadow-lg);
}
.toast-show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ---------- Focus-visible 无障碍 ---------- */
a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* ---------- 平板断点 768-1024px ---------- */
@media (min-width: 769px) and (max-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ---------- 返回顶部按钮 ---------- */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 44px;
  height: 44px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1.2rem;
  cursor: pointer;
  z-index: 90;
  opacity: 0;
  transform: translateY(10px);
  transition: opacity .3s, transform .3s, background .2s;
  box-shadow: var(--shadow-md);
  display: flex;
  align-items: center;
  justify-content: center;
}
.back-to-top-show {
  opacity: 1;
  transform: translateY(0);
}
.back-to-top:hover {
  background: var(--primary-dark);
}

/* ---------- 购买引导弹窗 ---------- */
.purchase-guide {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-md);
  opacity: 0;
  transition: opacity .3s;
}
.purchase-guide-show { opacity: 1; }
.purchase-guide-box {
  background: #fff;
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  max-width: 380px;
  width: 100%;
  position: relative;
  transform: translateY(10px);
  transition: transform .3s;
}
.purchase-guide-show .purchase-guide-box { transform: translateY(0); }
.purchase-guide-close {
  position: absolute;
  top: 12px;
  right: 16px;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-light);
  cursor: pointer;
}

/* ---------- 搜索框 ---------- */
.search-wrap {
  position: relative;
  max-width: 320px;
  margin: 0 auto var(--space-lg);
}
.search-wrap input {
  width: 100%;
  padding: 10px 16px 10px 38px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: .9rem;
  background: #fff;
  transition: border-color .2s;
}
.search-wrap input:focus {
  border-color: var(--primary);
  outline: none;
}
.search-wrap::before {
  content: "🔍";
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-size: .9rem;
  pointer-events: none;
}
.search-results {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  z-index: 110;
  max-height: 300px;
  overflow-y: auto;
}

/* ---------- 卡片触摸反馈 ---------- */
.card:active {
  transform: scale(0.98);
  transition: transform .1s;
}
.btn:active {
  transform: scale(0.97);
  transition: transform .1s;
}
.amount-btn:active {
  transform: scale(0.95);
}

/* ---------- 自定义金额输入框 ---------- */
.custom-amount-wrap {
  display: flex;
  align-items: center;
  gap: 8px;
  justify-content: center;
  margin-top: var(--space-sm);
}
.custom-amount-wrap label {
  font-size: .9rem;
  color: var(--text-secondary);
  font-weight: 600;
}
.custom-amount-wrap input {
  width: 100px;
  padding: 8px 12px;
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  font-size: .95rem;
  text-align: center;
  font-weight: 600;
  transition: border-color .2s;
}
.custom-amount-wrap input:focus {
  border-color: var(--primary);
  outline: none;
}
.custom-amount-wrap span {
  font-size: .9rem;
  color: var(--text-secondary);
}

/* ---------- 搜索结果链接hover ---------- */
.search-results a:hover {
  background: var(--bg-secondary);
}

@media (max-width: 768px) {
  .back-to-top { bottom: 20px; right: 20px; width: 40px; height: 40px; }
  .search-wrap { max-width: 100%; }
}

/* ---------- 修复: active覆盖hover transform ---------- */
.card:hover {
  transform: translateY(-4px);
}
.card:active {
  transform: scale(0.98) !important;
  transition: transform .1s !important;
}

/* ---------- 修复: 480px以下统计数字纵向排列 ---------- */
@media (max-width: 480px) {
  .hero-stats {
    flex-direction: column;
    gap: var(--space-md);
  }
}

/* ---------- 移动端折叠目录 ---------- */
.toc-toggle {
  display: none;
  width: 100%;
  padding: 10px 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: .9rem;
  font-weight: 600;
  color: var(--text);
  text-align: left;
  cursor: pointer;
  margin-bottom: var(--space-sm);
}
.toc-toggle::after {
  content: " ▼";
  font-size: .7rem;
}
@media (max-width: 768px) {
  .toc-toggle { display: block; }
  .toc { display: none; }
  .toc.toc-open { display: block; position: static; max-height: none; }
}


/* ---------- 支付引导弹窗 ---------- */
.checkout-guide {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  z-index: 210;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-md);
  opacity: 0;
  transition: opacity .3s;
}
.checkout-guide-show { opacity: 1; }
.checkout-box {
  background: #fff;
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  max-width: 420px;
  width: 100%;
  position: relative;
  transform: translateY(10px);
  transition: transform .3s;
  box-shadow: var(--shadow-lg);
}
.checkout-guide-show .checkout-box { transform: translateY(0); }