/* ════════════════════════════════════════════════
   AI工具宝箱 — 优化版 CSS
   优化方向：视觉卡片感 · 移动端响应 · 性能 · SEO结构
   ════════════════════════════════════════════════ */

/* ─── CSS 变量 ─── */
:root {
  --primary:       #4f46e5;
  --primary-light: #6366f1;
  --secondary:     #7c3aed;
  --accent:        #06b6d4;
  --bg-gradient:   linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);

  --text-main:   #1e293b;
  --text-muted:  #64748b;
  --text-light:  #f8fafc;

  --body-bg:    #f1f5f9;
  --surface:    #ffffff;
  --surface-2:  #f8fafc;

  --glass-bg:     rgba(255,255,255,0.15);
  --glass-border: rgba(255,255,255,0.3);

  --shadow-xs: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.07);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.09);
  --shadow-lg: 0 10px 30px rgba(0,0,0,0.12);
  --shadow-hover: 0 20px 40px rgba(79,70,229,0.18);
  --shadow-card: 0 2px 12px rgba(0,0,0,0.06), 0 0 0 1px rgba(0,0,0,0.04);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-pill: 9999px;

  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);

  /* 分类颜色系统 */
  --cat-chat:    #10b981;
  --cat-write:   #6366f1;
  --cat-image:   #f59e0b;
  --cat-code:    #3b82f6;
  --cat-video:   #ef4444;
  --cat-audio:   #8b5cf6;
  --cat-office:  #0ea5e9;
  --cat-design:  #ec4899;
  --cat-search:  #14b8a6;
  --cat-trans:   #22c55e;
  --cat-auto:    #f97316;
  --cat-eff:     #a855f7;
}

/* ─── 全局重置 ─── */
*, *::before, *::after {
  margin: 0; padding: 0;
  box-sizing: border-box;
}
html {
  width: 100%;
  overflow-x: hidden;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
               'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--body-bg);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  width: 100%;
  overflow-x: hidden;
}

/* ─── 滚动条 ─── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--body-bg); }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: var(--radius-pill); }

/* ════════════════════════════════════════════════
   HEADER
   ════════════════════════════════════════════════ */
.header {
  background: var(--surface);
  border-bottom: 1px solid rgba(0,0,0,0.07);
  box-shadow: 0 1px 10px rgba(0,0,0,0.05);
  position: sticky;
  top: 0;
  z-index: 200;
}
.header-inner {
  padding: 12px 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.header h1 {
  font-size: 22px;
  font-weight: 800;
  background: var(--bg-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: flex;
  align-items: center;
  gap: 8px;
  letter-spacing: -0.5px;
  white-space: nowrap;
}
.header h1 span {
  font-size: 12px;
  font-weight: 500;
  -webkit-text-fill-color: var(--text-muted);
  margin-left: 8px;
  opacity: 0.85;
}

/* 全局导航 */
.global-nav {
  border-top: 1px solid #f1f5f9;
}
.global-nav-inner {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 6px 32px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.global-nav-inner::-webkit-scrollbar { display: none; }
.gn-item {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  white-space: nowrap;
  transition: var(--transition);
  border: 1px solid transparent;
}
.gn-item:hover {
  background: linear-gradient(135deg, rgba(79,70,229,0.07), rgba(124,58,237,0.07));
  color: var(--primary);
  border-color: rgba(79,70,229,0.12);
}

/* ─── 搜索框（导航栏下方） ─── */
.search-bar-below-nav {
  background: var(--surface);
  border-bottom: 1px solid #f1f5f9;
  padding: 12px 32px;
}
.search-bar-inner { max-width: 660px; margin: 0 auto; }

.search-box {
  display: flex;
  background: var(--body-bg);
  border: 1.5px solid #e2e8f0;
  border-radius: var(--radius-pill);
  overflow: hidden;
  transition: var(--transition);
}
.search-box:focus-within {
  background: var(--surface);
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79,70,229,0.12);
}
.search-box input {
  flex: 1;
  border: none;
  background: transparent;
  padding: 13px 22px;
  color: var(--text-main);
  font-size: 15px;
  outline: none;
  min-width: 0;
}
.search-box input::placeholder { color: #94a3b8; }
.search-box button {
  border: none;
  background: transparent;
  color: var(--text-muted);
  padding: 13px 20px;
  cursor: pointer;
  font-size: 18px;
  transition: var(--transition);
  flex-shrink: 0;
}
.search-box button:hover { color: var(--primary); transform: scale(1.1); }

/* header 内搜索隐藏 */
.header-inner .search-box { display: none; }

/* ════════════════════════════════════════════════
   MAIN LAYOUT — 修复 CSS 顺序 Bug
   ════════════════════════════════════════════════ */
.container {
  width: 100%;
  box-sizing: border-box;
  padding: 40px 32px;
}

/* 首页双栏容器 */
.home-container {
  width: 100%;
  padding: 28px 32px;
  display: grid;
  grid-template-columns: minmax(140px, 176px) 1fr;
  gap: 0;
  align-items: start;
}

/* 左侧分类竖导航 */
.sidebar-nav {
  position: sticky;
  top: 118px;
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 12px 16px 12px 0;
  border-right: 1px solid #e8edf3;
  margin-right: 24px;
  min-height: 300px;
}
.sidebar-cat {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 14px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 13.5px;
  font-weight: 500;
  transition: var(--transition);
  text-align: left;
  white-space: nowrap;
  width: 100%;
}
.sidebar-cat:hover {
  background: #f1f5f9;
  color: var(--primary);
  transform: translateX(2px);
}
.sidebar-cat.active {
  background: linear-gradient(135deg, rgba(79,70,229,0.1), rgba(124,58,237,0.08));
  color: var(--primary);
  font-weight: 700;
  border-color: rgba(79,70,229,0.18);
}

/* !! 关键修复：.main-layout-no-sidebar 必须定义在 .main-layout 之后 !! */
.main-layout {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 40px;
  align-items: start;
}
/* 覆盖 .main-layout，去掉右侧空列 */
.main-layout-no-sidebar {
  display: block !important;
  width: 100%;
  min-width: 0;
}

/* 移动端分类横滚（默认隐藏） */
.mobile-categories { display: none; }

/* ════════════════════════════════════════════════
   HERO 区
   ════════════════════════════════════════════════ */
.hero {
  background: var(--bg-gradient);
  padding: 72px 24px;
  text-align: center;
  color: var(--text-light);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -40%; left: -8%;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(255,255,255,0.18) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}
.hero::after {
  content: '';
  position: absolute;
  bottom: -30%; right: -4%;
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(255,255,255,0.12) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}
.hero h2 {
  font-size: 42px;
  font-weight: 800;
  margin-bottom: 18px;
  letter-spacing: -1px;
  text-shadow: 0 2px 12px rgba(0,0,0,0.12);
  position: relative;
}
.hero p {
  font-size: 17px;
  opacity: 0.93;
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
  position: relative;
}
.hero .stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 36px;
  position: relative;
  flex-wrap: wrap;
}
.hero .stat {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  padding: 14px 28px;
  border-radius: var(--radius-md);
  text-align: center;
  transition: var(--transition);
}
.hero .stat:hover { transform: translateY(-4px); background: rgba(255,255,255,0.22); }
.hero .stat .num { font-size: 32px; font-weight: 800; }
.hero .stat .label { font-size: 12px; opacity: 0.88; text-transform: uppercase; letter-spacing: 1px; }

/* ════════════════════════════════════════════════
   SECTION 通用
   ════════════════════════════════════════════════ */
.section, .home-section { margin-bottom: 44px; }
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  padding-bottom: 14px;
  border-bottom: 2px solid #e8edf3;
  position: relative;
}
/* 渐变下划线装饰 */
.section-header::after {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 60px; height: 2px;
  background: var(--bg-gradient);
  border-radius: 2px;
}
.section h3 {
  font-size: 20px;
  font-weight: 800;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 8px;
}
.section h3 span {
  font-size: 11px;
  background: #ffe4e6;
  color: #e11d48;
  padding: 3px 9px;
  border-radius: var(--radius-pill);
  letter-spacing: 0.8px;
  font-weight: 700;
}
.today-section .section-header h3 span { background: #dcfce7; color: #16a34a; }
.hot-section   .section-header h3 span { background: #ffedd5; color: #ea580c; }
.all-section   .section-header h3 span { background: #ede9fe; color: var(--primary); }
.tool-count { font-size: 13px; color: var(--text-muted); font-weight: 500; }
.section a {
  color: var(--primary);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  transition: var(--transition);
}
.section a:hover { color: var(--secondary); }

/* ════════════════════════════════════════════════
   工具卡片 — 卡片丰富感
   ════════════════════════════════════════════════ */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 18px;
}
.tool-card {
  background: var(--surface);
  border-radius: var(--radius-lg);
  padding: 0;
  box-shadow: var(--shadow-card);
  border: 1px solid rgba(0,0,0,0.05);
  transition: var(--transition);
  cursor: pointer;
  position: relative;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  will-change: transform;
}
/* 彩色顶部装饰条 */
.tool-card::before {
  content: '';
  display: block;
  height: 3px;
  background: var(--bg-gradient);
  flex-shrink: 0;
}
.tool-card-body {
  padding: 20px 20px 40px;
  display: flex;
  flex-direction: column;
  flex: 1;
}
.tool-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
  border-color: rgba(79,70,229,0.18);
}
.tool-card:active { transform: translateY(-2px); }
.tool-card.fade-in { animation: slideUp 0.45s ease backwards; }

@keyframes slideUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

.tool-icon {
  width: 52px; height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 26px;
  margin-bottom: 14px;
  box-shadow: inset 0 -2px 4px rgba(0,0,0,0.07);
  flex-shrink: 0;
}
.tool-card h4 {
  font-size: 17px;
  margin-bottom: 8px;
  color: var(--text-main);
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}
.tool-card .desc {
  font-size: 13.5px;
  color: var(--text-muted);
  line-height: 1.65;
  margin-bottom: 14px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  flex-grow: 1;
}
.tool-card .tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}
.tool-card .tag {
  font-size: 11.5px;
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  background: #f1f5f9;
  color: var(--text-muted);
  font-weight: 600;
  transition: var(--transition);
}
.tool-card:hover .tag { background: #ede9fe; color: var(--primary); }
.tool-card .tag.hot  { background: #fff1f2; color: #f43f5e; }
.tool-card .tag.free { background: #f0fdf4; color: #16a34a; }
.tool-card .meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 12px;
  border-top: 1px dashed #e8edf3;
}
.tool-card .rating { color: #f59e0b; font-size: 13px; font-weight: 700; display: flex; align-items: center; gap: 4px; }
.tool-card .visits { color: #94a3b8; font-size: 12px; display: flex; align-items: center; gap: 4px; }

/* 查看详情提示 */
.tool-card::after {
  content: '查看详情 →';
  position: absolute;
  bottom: 14px;
  right: 18px;
  font-size: 11.5px;
  color: var(--primary);
  font-weight: 700;
  opacity: 0;
  transform: translateX(-6px);
  transition: all 0.2s ease;
}
.tool-card:hover::after { opacity: 1; transform: translateX(0); }

/* ════════════════════════════════════════════════
   BADGE 角标
   ════════════════════════════════════════════════ */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 7px;
  border-radius: var(--radius-sm);
  font-size: 10.5px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  flex-shrink: 0;
}
.badge-new  { background: linear-gradient(135deg,#10b981,#059669); color:#fff; }
.badge-hot  { background: linear-gradient(135deg,#f43f5e,#e11d48); color:#fff; }
.badge-pick { background: linear-gradient(135deg,#f59e0b,#d97706); color:#fff; }

/* ════════════════════════════════════════════════
   CONTENT TABS（AI前沿/辞典/实战）
   ════════════════════════════════════════════════ */
.content-tabs {
  margin-bottom: 28px;
  display: grid;
  grid-template-columns: 156px 1fr;
  background: var(--surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(0,0,0,0.05);
  overflow: hidden;
}
.content-tabs-nav {
  display: flex;
  flex-direction: column;
  padding: 10px 6px;
  background: var(--surface-2);
  border-right: 1px solid #e8edf3;
  gap: 2px;
}
.tab-card {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 12px;
  border: none;
  border-radius: var(--radius-md);
  background: transparent;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  width: 100%;
  height: 108px;
}
.tab-card:hover { background: var(--surface); box-shadow: var(--shadow-xs); }
.tab-card.active { background: var(--surface); box-shadow: 0 2px 10px rgba(79,70,229,0.12); }
.tab-card-icon {
  font-size: 20px;
  width: 36px; height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  background: #f1f5f9;
  flex-shrink: 0;
  transition: var(--transition);
}
.tab-card.active .tab-card-icon { background: linear-gradient(135deg, rgba(79,70,229,0.1), rgba(124,58,237,0.1)); }
.tab-card-text { display: flex; flex-direction: column; gap: 2px; }
.tab-card-title { font-size: 14px; font-weight: 700; color: var(--text-main); line-height: 1.3; }
.tab-card.active .tab-card-title { color: var(--primary); }
.tab-card-desc { font-size: 11px; color: #94a3b8; }
.tab-card.active .tab-card-desc { color: rgba(79,70,229,0.65); }

.content-tabs-body { padding: 18px 22px; height: 340px; overflow-y: auto; }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* 新闻列表 */
.news-cards { display: flex; flex-direction: column; gap: 1px; }
.news-card-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 10px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: background .15s;
  border-bottom: 1px solid #f8fafc;
}
.news-card-item:last-child { border-bottom: none; }
.news-card-item:hover { background: #f8fafc; }
.news-card-date { font-size: 12px; color: #94a3b8; white-space: nowrap; min-width: 38px; font-weight: 600; }
.news-card-title {
  flex: 1; font-size: 13.5px; color: var(--text-main); font-weight: 500;
  display: -webkit-box; -webkit-line-clamp: 1; -webkit-box-orient: vertical; overflow: hidden;
}
.news-card-tag {
  font-size: 11px; padding: 2px 9px; border-radius: 16px;
  background: #f1f5f9; color: var(--text-muted); font-weight: 600;
  white-space: nowrap; flex-shrink: 0;
}
.news-card-item:hover .news-card-tag { background: #ede9fe; color: var(--primary); }
.news-card-item:hover .news-card-title { color: var(--primary); }
.news-card-more { justify-content: center; padding: 10px; margin-top: 4px; }
.news-card-more-text { font-size: 13px; font-weight: 700; color: var(--primary); }

/* AI辞典 */
.dict-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; }
.dict-card-item {
  display: flex; gap: 12px; padding: 14px;
  border-radius: var(--radius-md); text-decoration: none;
  border: 1px solid #f1f5f9; transition: var(--transition);
}
.dict-card-item:hover {
  border-color: rgba(79,70,229,0.18);
  background: #fafaff;
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}
.dict-card-icon {
  font-size: 26px; width: 44px; height: 44px; flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  background: var(--surface-2); border-radius: 10px;
}
.dict-card-body h4 { font-size: 13.5px; font-weight: 700; color: var(--text-main); margin-bottom: 4px; }
.dict-card-body p {
  font-size: 12.5px; color: var(--text-muted); line-height: 1.6;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}

/* 实战空状态 */
.practice-empty {
  display: flex; flex-direction: column; align-items: center;
  justify-content: center; padding: 40px 20px; text-align: center;
}
.practice-empty-icon { font-size: 44px; margin-bottom: 14px; opacity: 0.55; }
.practice-empty h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.practice-empty p { font-size: 13.5px; color: #94a3b8; line-height: 1.6; max-width: 320px; }

/* ════════════════════════════════════════════════
   NEWSLETTER
   ════════════════════════════════════════════════ */
.newsletter {
  background: var(--surface);
  border-radius: var(--radius-lg);
  padding: 44px 36px;
  text-align: center;
  margin-bottom: 44px;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-md);
  border: 1px solid rgba(0,0,0,0.04);
  display: flex;
  flex-direction: column;
  align-items: center;
}
.newsletter::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 4px;
  background: var(--bg-gradient);
}
.newsletter h3 {
  font-size: 24px; font-weight: 800; margin-bottom: 10px;
  background: var(--bg-gradient);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.newsletter p { color: var(--text-muted); margin-bottom: 22px; font-size: 15px; }
.newsletter .email-form { display: flex; gap: 10px; width: 100%; max-width: 460px; }
.newsletter input {
  flex: 1; padding: 14px 18px; border: 2px solid #e2e8f0;
  border-radius: var(--radius-md); font-size: 14px; outline: none; transition: var(--transition);
}
.newsletter input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79,70,229,0.1); }
.newsletter button {
  padding: 14px 28px; background: var(--bg-gradient); color: #fff;
  border: none; border-radius: var(--radius-md); font-weight: 700;
  font-size: 14px; cursor: pointer; transition: var(--transition); white-space: nowrap;
}
.newsletter button:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }

/* ════════════════════════════════════════════════
   FOOTER
   ════════════════════════════════════════════════ */
.footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 44px 24px;
  text-align: center;
  margin-top: 50px;
  border-top: 3px solid var(--primary);
  font-size: 14px;
}
.footer a { color: #cbd5e1; text-decoration: none; transition: var(--transition); }
.footer a:hover { color: #fff; }
.footer-links {
  margin-top: 22px;
  display: flex; justify-content: center;
  gap: 28px; flex-wrap: wrap;
}
.footer-links a { font-size: 13.5px; font-weight: 500; }

/* ════════════════════════════════════════════════
   BREADCRUMB & SIDEBAR CARD (其他页通用)
   ════════════════════════════════════════════════ */
.breadcrumb {
  max-width: 1200px; margin: -16px auto 18px;
  padding: 0 24px; font-size: 13px; color: var(--text-muted);
}
.breadcrumb a { color: var(--primary); text-decoration: none; font-weight: 500; }

.sidebar-card {
  background: var(--surface);
  border-radius: var(--radius-lg);
  padding: 22px;
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(0,0,0,0.04);
}
.sidebar-card h4 {
  font-size: 17px; margin-bottom: 18px; font-weight: 700;
  padding-bottom: 12px; border-bottom: 2px solid #f1f5f9;
}
.sidebar-card ul { list-style: none; }
.sidebar-card li { padding: 11px 0; border-bottom: 1px solid #f8fafc; font-size: 14px; }
.sidebar-card li:last-child { border-bottom: none; }
.sidebar-card li a { color: var(--text-main); text-decoration: none; font-weight: 500; transition: var(--transition); }
.sidebar-card li a:hover { color: var(--primary); padding-left: 4px; }
.sidebar-card-header {
  display: flex; align-items: center;
  justify-content: space-between;
  margin-bottom: 18px; padding-bottom: 12px;
  border-bottom: 2px solid #f1f5f9;
}
.sidebar-card-header h4 { font-size: 17px; color: var(--text-main); margin: 0; padding: 0; border: none; }
.sidebar-more-link {
  font-size: 13px; color: var(--primary);
  text-decoration: none; font-weight: 600;
  transition: var(--transition);
}
.sidebar-more-link:hover { color: var(--secondary); }

/* ════════════════════════════════════════════════
   返回顶部
   ════════════════════════════════════════════════ */
#backToTop {
  position: fixed;
  right: 24px; bottom: 32px;
  width: 44px; height: 44px;
  border-radius: 50%;
  background: var(--bg-gradient);
  color: #fff; border: none;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 4px 18px rgba(79,70,229,0.38);
  opacity: 0; transform: translateY(20px);
  transition: opacity 0.3s, transform 0.3s;
  z-index: 999; pointer-events: none;
}
#backToTop.visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
#backToTop:hover { box-shadow: 0 6px 24px rgba(79,70,229,0.52); transform: translateY(-3px); }
#backToTop svg { width: 20px; height: 20px; }

/* ════════════════════════════════════════════════
   工具详情页 / 文章页
   ════════════════════════════════════════════════ */
.article-container { max-width: 860px; margin: 0 auto; padding: 20px 24px 60px; }
.tool-header {
  background: var(--surface); border-radius: var(--radius-lg);
  padding: 28px; margin-bottom: 28px;
  box-shadow: var(--shadow-md); border: 1px solid rgba(0,0,0,0.04);
}
.tool-header-top { display: flex; gap: 22px; align-items: flex-start; margin-bottom: 22px; }
.tool-icon-lg { width: 76px; height: 76px; border-radius: var(--radius-md); display: flex; align-items: center; justify-content: center; font-size: 38px; flex-shrink: 0; }
.tool-header-info h2 { font-size: 26px; font-weight: 800; margin-bottom: 8px; display: flex; align-items: center; gap: 10px; }
.tool-header-info .subtitle { font-size: 15px; color: var(--text-muted); line-height: 1.6; margin-bottom: 10px; }
.tool-meta { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 10px; padding: 18px 0; border-top: 1px solid #e8edf3; border-bottom: 1px solid #e8edf3; margin-bottom: 18px; }
.tool-meta-item { font-size: 14px; color: var(--text-muted); }
.action-bar { display: flex; gap: 10px; }
.action-btn { display: inline-flex; align-items: center; padding: 13px 28px; border-radius: var(--radius-md); font-size: 15px; font-weight: 700; text-decoration: none; transition: var(--transition); cursor: pointer; }
.action-btn-primary { background: var(--bg-gradient); color: #fff; box-shadow: var(--shadow-md); }
.action-btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); color: #fff; }

.article-body {
  background: var(--surface); border-radius: var(--radius-lg); padding: 36px;
  margin-bottom: 28px; box-shadow: var(--shadow-sm); border: 1px solid rgba(0,0,0,0.04);
  line-height: 1.8; font-size: 16px; color: var(--text-main);
}
.article-body h1 { font-size: 30px; font-weight: 800; margin-bottom: 16px; }
.article-body h2 { font-size: 22px; font-weight: 700; margin: 30px 0 14px; padding-bottom: 8px; border-bottom: 2px solid #e8edf3; }
.article-body h3 { font-size: 19px; font-weight: 700; margin: 22px 0 10px; }
.article-body p { margin-bottom: 14px; color: #334155; }
.article-body ul, .article-body ol { padding-left: 22px; margin-bottom: 14px; }
.article-body li { margin-bottom: 6px; color: #334155; line-height: 1.7; }
.article-body code { background: #f1f5f9; padding: 2px 6px; border-radius: 4px; font-size: 13.5px; color: #e11d48; }
.article-body pre { background: #0f172a; color: #e2e8f0; padding: 20px; border-radius: var(--radius-md); overflow-x: auto; margin: 18px 0; font-size: 14px; }
.article-body pre code { background: transparent; color: inherit; padding: 0; }
.article-body blockquote { border-left: 4px solid var(--primary); padding: 10px 18px; margin: 14px 0; background: #f8fafc; border-radius: 0 var(--radius-sm) var(--radius-sm) 0; color: #475569; font-style: italic; }
.article-body table { width: 100%; border-collapse: collapse; margin: 18px 0; font-size: 14px; }
.article-body th { background: var(--bg-gradient); color: #fff; padding: 11px 14px; text-align: left; font-weight: 600; }
.article-body td { padding: 11px 14px; border-bottom: 1px solid #e8edf3; color: #334155; }
.article-body tr:hover td { background: #f8fafc; }

.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 10px; margin-bottom: 28px; }
.feature-item { background: var(--surface); padding: 14px; border-radius: var(--radius-md); text-align: center; font-size: 13.5px; font-weight: 600; box-shadow: var(--shadow-xs); border: 1px solid rgba(0,0,0,0.04); transition: var(--transition); }
.feature-item:hover { transform: translateY(-2px); color: var(--primary); }

.pros-cons { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-bottom: 28px; }
.pros-cons .pros, .pros-cons .cons { background: var(--surface); border-radius: var(--radius-lg); padding: 22px; box-shadow: var(--shadow-xs); border: 1px solid rgba(0,0,0,0.04); }
.pros-cons h4 { font-size: 17px; font-weight: 700; margin-bottom: 14px; }
.pros-cons ul { list-style: none; padding: 0; }
.pros-cons li { padding: 7px 0; border-bottom: 1px dashed #e8edf3; font-size: 13.5px; color: #334155; }
.pros-cons li:last-child { border-bottom: none; }

.related-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(155px, 1fr)); gap: 14px; }
.related-card { background: var(--surface); border-radius: var(--radius-md); padding: 18px; text-align: center; text-decoration: none; box-shadow: var(--shadow-xs); border: 1px solid rgba(0,0,0,0.04); transition: var(--transition); }
.related-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: rgba(79,70,229,0.18); }

/* 文章列表 */
.articles-list { display: flex; flex-direction: column; gap: 18px; margin-bottom: 36px; }
.article-card { background: var(--surface); border-radius: var(--radius-md); padding: 22px; border: 1px solid rgba(0,0,0,0.05); box-shadow: var(--shadow-xs); transition: var(--transition); }
.article-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.article-card h3 { font-size: 17px; font-weight: 700; margin: 0 0 7px; line-height: 1.5; }
.article-card h3 a { color: var(--text-main); text-decoration: none; }
.article-card h3 a:hover { color: var(--primary); }
.article-meta { display: flex; gap: 10px; font-size: 12.5px; color: var(--text-muted); margin-bottom: 8px; }
.article-card .summary { font-size: 14px; color: #475569; line-height: 1.7; margin: 0; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }

/* 分页 */
.pagination { display: flex; align-items: center; justify-content: center; gap: 14px; padding: 28px 0 14px; }
.pagination a { display: inline-flex; align-items: center; padding: 9px 18px; background: var(--primary); color: #fff; border-radius: var(--radius-sm); font-size: 14px; font-weight: 600; text-decoration: none; transition: var(--transition); }
.pagination a:hover { background: var(--secondary); transform: translateY(-1px); }
.pagination .page-info { font-size: 13px; color: var(--text-muted); min-width: 56px; text-align: center; }

/* Live Dashboard（保留） */
.live-nav { background: var(--primary); border-bottom: 2px solid rgba(255,255,255,0.1); padding: 0; position: sticky; top: 60px; z-index: 90; }
.live-nav .container { display: flex; overflow-x: auto; scrollbar-width: none; }
.live-nav .container::-webkit-scrollbar { display: none; }
.live-nav a { display: block; padding: 13px 18px; color: rgba(255,255,255,0.75); text-decoration: none; font-size: 13.5px; font-weight: 500; white-space: nowrap; border-bottom: 3px solid transparent; transition: all 0.2s; }
.live-nav a:hover { color: #fff; background: rgba(255,255,255,0.08); }
.live-nav a.active { color: #fff; border-bottom-color: #fbbf24; background: rgba(255,255,255,0.12); }
.live-section { background: var(--surface); border-radius: var(--radius-md); padding: 26px; margin-bottom: 22px; box-shadow: var(--shadow-sm); border: 1px solid rgba(0,0,0,0.04); }
.live-section h2 { font-size: 20px; font-weight: 700; margin-bottom: 6px; }
.live-section .desc { color: var(--text-muted); font-size: 14px; margin-bottom: 18px; }
.live-stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 14px; margin-bottom: 22px; }
.stat-card { background: var(--surface); border-radius: var(--radius-md); padding: 18px 14px; text-align: center; box-shadow: var(--shadow-xs); border: 1px solid rgba(0,0,0,0.04); transition: var(--transition); }
.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.stat-card.stat-primary { background: var(--bg-gradient); color: #fff; border: none; }
.stat-card.stat-primary .stat-label { color: rgba(255,255,255,0.85); }
.stat-number { font-size: 26px; font-weight: 800; color: var(--text-main); }
.stat-card.stat-primary .stat-number { color: #fff; }
.stat-label { font-size: 12.5px; color: var(--text-muted); margin-top: 4px; }
.table-responsive { overflow-x: auto; -webkit-overflow-scrolling: touch; border-radius: var(--radius-sm); }
.live-matrix-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.live-matrix-table th { padding: 11px 13px; text-align: left; font-weight: 600; font-size: 13px; border-bottom: 2px solid var(--primary); background: var(--body-bg); }
.live-matrix-table td { padding: 11px 13px; border-bottom: 1px solid #f1f5f9; color: var(--text-main); vertical-align: middle; }
.live-matrix-table tbody tr:hover { background: #f8fafc; }
.badge-yes { color: #10b981; font-weight: 700; }
.badge-no  { color: #ef4444; font-weight: 700; }
.star-level { color: #f59e0b; letter-spacing: 1px; }
.btn.btn-sm { display: inline-block; padding: 7px 16px; font-size: 13px; background: var(--primary); color: #fff; border-radius: var(--radius-sm); text-decoration: none; font-weight: 600; transition: var(--transition); }
.btn.btn-sm:hover { background: var(--secondary); color: #fff; }
.btn.btn-xs { display: inline-block; padding: 4px 11px; font-size: 12px; background: var(--primary); color: #fff; border-radius: 6px; text-decoration: none; font-weight: 600; transition: var(--transition); }
.btn.btn-xs:hover { background: var(--secondary); color: #fff; }
.methodology-note { background: #fffbeb; border: 1px solid #fde68a; border-radius: var(--radius-sm); padding: 14px 18px; font-size: 13px; color: #92400e; margin-top: 10px; line-height: 1.6; }
.last-update { display: inline-block; font-size: 12.5px; color: var(--text-muted); background: var(--body-bg); padding: 5px 12px; border-radius: 20px; margin-top: 6px; }
.battle-preview-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(270px, 1fr)); gap: 14px; }
.battle-preview-card { background: var(--body-bg); border-radius: var(--radius-sm); padding: 18px; border-left: 4px solid var(--primary); }
.battle-preview-card h4 { font-size: 14px; font-weight: 700; margin-bottom: 7px; }
.battle-preview-card .verdict-sm { font-size: 12.5px; color: var(--text-muted); line-height: 1.6; margin-bottom: 10px; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.trend-cards-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: 12px; }
.trend-card { background: var(--body-bg); border-radius: var(--radius-sm); padding: 14px; border-left: 4px solid #94a3b8; transition: var(--transition); }
.trend-card:hover { transform: translateY(-2px); }
.trend-card.trend-hot { border-left-color: #ef4444; }
.trend-card.trend-up  { border-left-color: #10b981; }
.trend-card.trend-stable { border-left-color: #f59e0b; }
.trend-big-num { font-size: 24px; font-weight: 800; color: var(--text-main); }
.battle-card { background: var(--surface); border-radius: var(--radius-md); padding: 26px; box-shadow: var(--shadow-sm); border: 1px solid rgba(0,0,0,0.04); }
.battle-title { font-size: 19px; font-weight: 700; text-align: center; margin-bottom: 18px; }
.battle-vs { display: flex; align-items: center; justify-content: center; gap: 18px; margin-bottom: 22px; }
.score { font-size: 38px; font-weight: 900; color: var(--primary); }
.vs-badge { display: inline-flex; align-items: center; justify-content: center; width: 44px; height: 44px; background: var(--bg-gradient); color: #fff; font-size: 13px; font-weight: 800; border-radius: 50%; }
.battle-verdict { background: linear-gradient(135deg, #eff6ff, #f0f9ff); border: 1px solid #bfdbfe; border-radius: var(--radius-sm); padding: 14px 18px; font-size: 14px; color: #1e40af; line-height: 1.7; }
.heatmap-container { display: flex; flex-direction: column; gap: 6px; }
.heat-row { display: grid; grid-template-columns: 180px 1fr 120px; gap: 10px; align-items: stretch; padding: 10px 0; border-bottom: 1px solid #f1f5f9; }
.heat-cell { flex: 1; border-radius: var(--radius-sm); padding: 10px 12px; border: 1px solid; display: flex; flex-direction: column; gap: 2px; transition: transform .15s; }
.heat-cell:hover { transform: scale(1.02); }
.heat-label { font-size: 11.5px; font-weight: 600; color: rgba(255,255,255,0.85); }
.heat-count { font-size: 17px; font-weight: 800; color: #fff; }
.heat-tools { font-size: 10.5px; color: rgba(255,255,255,0.7); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.price-dist-bar { display: flex; border-radius: var(--radius-sm); overflow: hidden; }
.price-badge { font-size: 12px; font-weight: 700; padding: 3px 10px; border-radius: 12px; color: #fff; }
.price-badge.free { background: #10b981; }
.price-badge.freemium { background: #f59e0b; }
.price-badge.paid { background: #ef4444; }
.price-count { font-size: 17px; font-weight: 700; color: var(--text-main); }
.trend-preview-list { display: flex; flex-direction: column; gap: 7px; }
.trend-row { display: flex; align-items: center; gap: 10px; padding: 9px 14px; background: var(--body-bg); border-radius: var(--radius-sm); font-size: 14px; }
.trend-cat-name { font-weight: 600; color: var(--text-main); flex: 1; }
.trend-cat-val { font-weight: 700; color: var(--text-main); min-width: 36px; text-align: right; }
.spark-line { margin-top: 6px; }
.spark-line svg { display: block; width: 100%; height: 38px; }
.battle-dim-table { width: 100%; border-collapse: collapse; font-size: 13.5px; margin-bottom: 18px; }
.battle-dim-table th { padding: 9px 12px; text-align: left; font-weight: 600; font-size: 12.5px; border-bottom: 2px solid var(--primary); background: var(--body-bg); }
.battle-dim-table td { padding: 9px 12px; border-bottom: 1px solid #f1f5f9; }
.battle-dim-table .dim-val-a, .battle-dim-table .dim-val-b { text-align: center; font-size: 12.5px; }

/* ════════════════════════════════════════════════
   RESPONSIVE — 平板 (<992px)
   ════════════════════════════════════════════════ */
@media (max-width: 992px) {
  .hero { padding: 48px 18px; }
  .hero h2 { font-size: 32px; }
  .hero p  { font-size: 16px; }
  .hero .stats { gap: 20px; margin-top: 24px; }
  .hero .stat { padding: 12px 18px; }
  .hero .stat .num { font-size: 28px; }

  .home-container {
    grid-template-columns: minmax(110px, 136px) 1fr;
    padding: 20px 18px;
  }
  .sidebar-cat { font-size: 12.5px; padding: 8px 10px; }

  .container { padding: 22px 18px; }
  .tools-grid { grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 14px; }
  .newsletter { padding: 30px 20px; }
  .newsletter .email-form { flex-direction: column; }
  .article-body { padding: 26px 20px; }
  .main-layout { grid-template-columns: 1fr; }
  .live-stats-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .stat-number { font-size: 22px; }
  .trend-cards-grid { grid-template-columns: 1fr 1fr; gap: 10px; }
  .battle-preview-grid { grid-template-columns: 1fr; }
}

/* ════════════════════════════════════════════════
   RESPONSIVE — 手机 (<768px)
   ════════════════════════════════════════════════ */
@media (max-width: 768px) {
  /* Header */
  .header-inner { padding: 10px 16px; }
  .global-nav-inner { padding: 5px 14px; gap: 0; }
  .gn-item { padding: 5px 10px; font-size: 12px; }

  /* 搜索 */
  .search-bar-below-nav { padding: 10px 16px; }
  .search-box input { padding: 12px 16px; font-size: 14px; }

  /* 首页布局：单列 */
  .home-container {
    grid-template-columns: 1fr;
    padding: 16px;
    gap: 0;
  }
  /* PC左侧导航隐藏 → 手机横排 */
  .sidebar-nav { display: none; }
  .mobile-categories {
    display: flex; gap: 7px; flex-wrap: nowrap;
    overflow-x: auto; -webkit-overflow-scrolling: touch;
    padding-bottom: 10px; margin-bottom: 20px;
    scrollbar-width: none;
  }
  .mobile-categories::-webkit-scrollbar { display: none; }
  .cat-btn {
    padding: 8px 15px; font-size: 13px;
    border: 1.5px solid #e2e8f0; border-radius: var(--radius-pill);
    background: var(--surface); color: var(--text-muted);
    cursor: pointer; font-weight: 600; white-space: nowrap; flex-shrink: 0;
    transition: var(--transition);
  }
  .cat-btn.active { background: var(--bg-gradient); color: #fff; border-color: transparent; }

  /* Hero */
  .hero { padding: 36px 16px; }
  .hero h2 { font-size: 24px; margin-bottom: 12px; }
  .hero p  { font-size: 15px; }
  .hero .stats { gap: 10px; margin-top: 20px; }
  .hero .stat { padding: 10px 14px; flex: 1 1 auto; min-width: 0; }
  .hero .stat .num { font-size: 22px; }
  .hero .stat .label { font-size: 10px; }

  /* 工具卡片 */
  .tools-grid { grid-template-columns: 1fr 1fr; gap: 12px; }
  .tool-card-body { padding: 14px 14px 36px; }
  .tool-icon { width: 44px; height: 44px; font-size: 22px; margin-bottom: 10px; }
  .tool-card h4 { font-size: 14px; }
  .tool-card .desc { font-size: 12.5px; -webkit-line-clamp: 3; }
  .tool-card:hover { transform: none; }
  .tool-card::after { opacity: 0.6; transform: translateX(0); }

  /* Content Tabs */
  .content-tabs { grid-template-columns: 100px 1fr; }
  .content-tabs-nav { padding: 8px 4px; }
  .tab-card { padding: 10px 8px; height: auto; gap: 6px; }
  .tab-card-icon { width: 28px; height: 28px; font-size: 15px; }
  .tab-card-title { font-size: 12px; }
  .tab-card-desc { font-size: 10px; }
  .content-tabs-body { padding: 12px; height: 270px; }
  .dict-cards { grid-template-columns: 1fr; gap: 8px; }

  /* Section */
  .section, .home-section { margin-bottom: 28px; }
  .section h3 { font-size: 17px; }
  .section-header { margin-bottom: 14px; }

  /* 工具详情 */
  .article-container { padding: 12px 12px 40px; }
  .tool-header { padding: 18px 15px; }
  .tool-header-top { flex-direction: column; align-items: center; text-align: center; }
  .tool-header-info h2 { font-size: 21px; justify-content: center; }
  .tool-icon-lg { width: 58px; height: 58px; font-size: 30px; }
  .tool-meta { grid-template-columns: 1fr 1fr; gap: 8px; }
  .action-bar { flex-direction: column; }
  .action-btn { padding: 12px 22px; font-size: 14px; text-align: center; justify-content: center; }
  .features-grid { grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: 8px; }
  .article-body { padding: 18px 14px; font-size: 15px; }
  .article-body h2 { font-size: 19px; }
  .article-body h3 { font-size: 16px; }
  .pros-cons { grid-template-columns: 1fr; }
  .related-grid { grid-template-columns: repeat(auto-fill, minmax(130px, 1fr)); gap: 10px; }

  /* Newsletter */
  .newsletter { padding: 22px 16px; }
  .newsletter h3 { font-size: 19px; }
  .newsletter .email-form { flex-direction: column; }
  .newsletter button { width: 100%; }

  /* 面包屑 */
  .breadcrumb { padding: 0 12px; font-size: 12px; margin: -10px auto 12px; }

  /* Footer */
  .footer { padding: 30px 16px; }
  .footer-links { gap: 14px; }

  /* 返回顶部 */
  #backToTop { right: 14px; bottom: 18px; width: 40px; height: 40px; }

  /* Live */
  .live-stats-grid { grid-template-columns: 1fr 1fr; }
  .live-section { padding: 16px 13px; }
  .heat-row { grid-template-columns: 1fr; gap: 7px; padding: 10px; background: var(--body-bg); border-radius: var(--radius-sm); }
  .heat-category { flex-direction: row; align-items: center; gap: 7px; }
  .battle-card { padding: 16px 13px; }
  .score { font-size: 30px; }
}

/* ════════════════════════════════════════════════
   RESPONSIVE — 小屏手机 (<480px)
   ════════════════════════════════════════════════ */
@media (max-width: 480px) {
  .tools-grid { grid-template-columns: 1fr; gap: 10px; }
  .tool-card-body { padding: 14px 14px 36px; }
  .hero h2 { font-size: 21px; }
  .content-tabs { grid-template-columns: 86px 1fr; }
  .tab-card { flex-direction: column; align-items: center; text-align: center; padding: 8px 5px; }
  .tab-card-desc { display: none; }
  .tab-card-title { font-size: 11px; }
  .content-tabs-body { height: 240px; padding: 10px; }
  .tool-meta { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .article-body { padding: 14px 12px; }
  .price-dist-bar { flex-direction: column; }
  .trend-cards-grid { grid-template-columns: 1fr; }
  .battle-vs { gap: 10px; }
  .vs-badge { width: 36px; height: 36px; font-size: 12px; }
}