/* ===== FreeAIStack Design System ===== */
:root {
  --primary: #165DFF;
  --primary-light: #e8efff;
  --primary-hover: #0e42d2;
  --accent: #36CFC9;
  --accent-light: #e0faf8;
  --text-primary: #1D2129;
  --text-secondary: #6E7681;
  --text-muted: #9ea4aa;
  --bg-site: #F7F8FA;
  --bg-card: #FFFFFF;
  --bg-alt: #f0f2f5;
  --shadow-card: 0 2px 14px rgba(0,0,0,0.06);
  --shadow-hover: 0 8px 28px rgba(0,0,0,0.10);
  --radius: 12px;
  --radius-lg: 16px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --section-gap: 80px;
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font);
  color: var(--text-primary);
  background: var(--bg-site);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary); text-decoration: none; transition: all 0.2s; }
a:hover { opacity: 0.85; }

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

/* ===== Nav ===== */
.nav {
  position: fixed; top: 0; left: 0; right: 0;
  background: rgba(255,255,255,0.96);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(0,0,0,0.04);
  z-index: 100;
  height: 60px;
}
.nav-inner {
  max-width: 1200px; margin: 0 auto;
  display: flex; align-items: center;
  justify-content: space-between;
  height: 100%; padding: 0 24px;
}
.nav-logo { font-weight: 800; font-size: 1.25rem; color: var(--text-primary); letter-spacing: -0.3px; }
.nav-logo span { color: var(--primary); }
.nav-menu { display: flex; gap: 32px; align-items: center; }
.nav-menu a { font-size: 0.88rem; color: var(--text-secondary); font-weight: 500; position: relative; }
.nav-menu a::after {
  content: ''; position: absolute; bottom: -4px; left: 0; width: 0; height: 2px;
  background: var(--primary); border-radius: 2px; transition: width 0.25s;
}
.nav-menu a:hover { color: var(--primary); }
.nav-menu a:hover::after { width: 100%; }
.nav-hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; background: none; border: none; padding: 4px; }
.nav-hamburger span { display: block; width: 22px; height: 2px; background: var(--text-primary); border-radius: 2px; transition: 0.25s; }

/* ===== Main ===== */
main { padding-top: 60px; }

/* ===== Section ===== */
.section { padding: 60px 24px; }
.section-alt { background: var(--bg-card); }
.section-inner { max-width: 1200px; margin: 0 auto; }
.section-label {
  display: inline-block;
  font-size: 0.78rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.5px; color: var(--primary);
  background: var(--primary-light); padding: 4px 12px; border-radius: 20px;
  margin-bottom: 12px;
}
.section-title {
  font-size: 1.65rem; font-weight: 800;
  color: var(--text-primary); line-height: 1.25;
  margin-bottom: 8px;
}
.section-subtitle {
  font-size: 0.95rem; color: var(--text-secondary);
  margin-bottom: 32px; max-width: 500px;
}

/* ===== Hero ===== */
.hero {
  text-align: center;
  padding: 100px 24px 80px;
  background: linear-gradient(180deg, #edf2ff 0%, var(--bg-site) 100%);
  position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute;
  top: -40%; right: -20%; width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(22,93,255,0.06) 0%, transparent 70%);
  pointer-events: none;
}
.hero::after {
  content: ''; position: absolute;
  bottom: -30%; left: -10%; width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(54,207,201,0.05) 0%, transparent 70%);
  pointer-events: none;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  line-height: 1.15;
  color: var(--text-primary);
  max-width: 700px;
  margin: 0 auto 16px;
  position: relative;
}
.hero .highlight { color: var(--primary); }
.hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 540px;
  margin: 0 auto;
  line-height: 1.6;
  position: relative;
}
.hero-stats {
  display: flex; justify-content: center; gap: 48px;
  margin-top: 40px; position: relative;
}
.hero-stats div { text-align: center; }
.hero-stats .num { font-size: 1.5rem; font-weight: 800; color: var(--text-primary); }
.hero-stats .label { font-size: 0.82rem; color: var(--text-muted); margin-top: 2px; }

/* ===== Category Grid ===== */
.cat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.cat-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  padding: 24px 20px;
  text-align: center;
  transition: all 0.3s ease;
  cursor: pointer;
  border: 1px solid transparent;
}
.cat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary-light);
}
.cat-card .icon { font-size: 2rem; margin-bottom: 10px; }
.cat-card h3 { font-size: 1rem; font-weight: 600; margin-bottom: 4px; }
.cat-card p { font-size: 0.83rem; color: var(--text-secondary); }

/* ===== Tool Card ===== */
.tool-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.tool-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  padding: 20px;
  display: flex; gap: 16px;
  transition: all 0.3s ease;
  border: 1px solid transparent;
}
.tool-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary-light);
}
.tool-card .thumb {
  width: 52px; height: 52px; min-width: 52px;
  border-radius: 10px;
  background: var(--primary-light);
  flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.4rem;
}
.tool-card .info { flex: 1; min-width: 0; }
.tool-card .info h3 { font-size: 0.95rem; font-weight: 600; margin-bottom: 4px; }
.tool-card .info p { font-size: 0.84rem; color: var(--text-secondary); line-height: 1.45; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.tool-card .tags { display: flex; gap: 6px; margin-top: 8px; flex-wrap: wrap; }
.tool-card .tags span {
  font-size: 0.72rem; padding: 2px 10px; border-radius: 20px;
  background: var(--primary-light); color: var(--primary); font-weight: 500;
}
.tool-card .badge-hot {
  font-size: 0.7rem; padding: 2px 10px; border-radius: 20px;
  background: #fff1e6; color: #cc5500; font-weight: 600;
}

/* ===== Collection Section ===== */
.collection-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.collection-card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  padding: 28px;
  transition: all 0.3s ease;
  border: 1px solid transparent;
  display: block;
}
.collection-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: var(--accent-light);
}
.collection-card .tag {
  display: inline-block; font-size: 0.7rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.3px; padding: 3px 10px; border-radius: 20px;
  background: var(--accent-light); color: #0a8a85; margin-bottom: 12px;
}
.collection-card h3 { font-size: 1.1rem; font-weight: 700; margin-bottom: 8px; }
.collection-card p { font-size: 0.85rem; color: var(--text-secondary); line-height: 1.55; }
.collection-card .count { font-size: 0.82rem; color: var(--primary); font-weight: 600; margin-top: 14px; }

/* ===== Trending Section ===== */
.trending-list { display: flex; flex-direction: column; gap: 10px; max-width: 700px; }
.trending-item {
  display: flex; align-items: center; gap: 14px;
  padding: 14px 18px; background: var(--bg-card);
  border-radius: 10px; box-shadow: var(--shadow-card);
  transition: all 0.25s ease;
}
.trending-item:hover { transform: translateX(4px); box-shadow: var(--shadow-hover); }
.trending-item .rank {
  font-size: 1rem; font-weight: 800; color: var(--text-muted);
  width: 24px; text-align: center; flex-shrink: 0;
}
.trending-item .rank.top3 { color: var(--primary); }
.trending-item .t-icon {
  width: 36px; height: 36px; border-radius: 8px;
  background: var(--primary-light); display: flex; align-items: center; justify-content: center;
  flex-shrink: 0; font-size: 1.1rem;
}
.trending-item .t-info { flex: 1; }
.trending-item .t-info h4 { font-size: 0.92rem; font-weight: 600; }
.trending-item .t-info p { font-size: 0.82rem; color: var(--text-secondary); }
.trending-item .t-badge {
  font-size: 0.7rem; padding: 2px 10px; border-radius: 20px;
  background: var(--primary-light); color: var(--primary); font-weight: 500; flex-shrink: 0;
}

/* ===== CTA Section ===== */
.cta-section {
  text-align: center; padding: 60px 24px;
  background: linear-gradient(135deg, var(--primary) 0%, #0e42d2 100%);
  color: white;
}
.cta-section h2 { font-size: 1.6rem; font-weight: 800; margin-bottom: 10px; }
.cta-section p { font-size: 0.95rem; opacity: 0.85; max-width: 460px; margin: 0 auto 24px; }
.cta-section .btn-sub {
  display: inline-block; padding: 12px 32px; border-radius: 10px;
  background: white; color: var(--primary); font-weight: 700; font-size: 0.9rem;
  transition: all 0.25s;
}
.cta-section .btn-sub:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.2); opacity: 1; }

/* ===== Footer ===== */
.footer {
  background: var(--bg-card);
  border-top: 1px solid #eef0f2;
  padding: 36px 24px;
  text-align: center;
  font-size: 0.84rem;
  color: var(--text-secondary);
}
.footer-links { display: flex; justify-content: center; gap: 24px; margin-bottom: 14px; }
.footer-links a { color: var(--text-secondary); font-weight: 500; }
.footer-links a:hover { color: var(--primary); }

/* ===== Ad Placeholders ===== */
.ad-banner {
  background: var(--bg-alt);
  border-radius: var(--radius);
  display: flex; align-items: center; justify-content: center;
  color: var(--text-muted); font-size: 0.75rem;
  margin: 24px 0; width: 100%; min-height: 90px;
}
.ad-mobile-bottom {
  display: none;
  position: fixed; bottom: 0; left: 0; right: 0;
  background: var(--bg-card); border-top: 1px solid #eef0f2;
  padding: 8px 20px; z-index: 99;
  text-align: center; font-size: 0.75rem; color: var(--text-muted);
}

/* ===== Review Page ===== */
.review-page { max-width: 720px; margin: 0 auto; padding: 40px 24px 60px; }
.review-page h1 { font-size: 1.75rem; font-weight: 800; line-height: 1.3; margin-bottom: 12px; }
.review-page .meta { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 24px; line-height: 1.6; }
.review-tool { margin-bottom: 32px; padding: 24px; background: var(--bg-card); border-radius: var(--radius); box-shadow: var(--shadow-card); }
.review-tool h2 { font-size: 1.2rem; font-weight: 700; margin-bottom: 8px; }
.review-tool .r-img { width: 100%; height: 180px; background: var(--primary-light); border-radius: 8px; margin: 12px 0; display: flex; align-items: center; justify-content: center; font-size: 2.5rem; }
.review-tool p { font-size: 0.9rem; color: var(--text-secondary); line-height: 1.6; margin-bottom: 8px; }
.compare-table { width: 100%; border-collapse: collapse; margin: 24px 0; font-size: 0.9rem; border-radius: 8px; overflow: hidden; }
.compare-table th { background: var(--primary); color: white; padding: 12px 14px; text-align: left; font-weight: 600; }
.compare-table td { padding: 10px 14px; border-bottom: 1px solid #eef0f2; }
.compare-table tr:nth-child(even) { background: #f8f9fa; }
.btn-link {
  display: inline-block;
  background: var(--primary);
  color: white !important;
  padding: 10px 22px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9rem;
  transition: all 0.2s;
}
.btn-link:hover { background: var(--primary-hover); transform: translateY(-1px); opacity: 1; }

/* ===== List Page ===== */
.list-header { padding: 50px 24px 32px; text-align: center; }
.list-header h1 { font-size: 1.75rem; font-weight: 800; }
.list-header p { color: var(--text-secondary); font-size: 0.95rem; margin-top: 8px; }
.filter-bar { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 24px; }
.filter-bar button {
  padding: 6px 18px; border-radius: 20px; border: 1px solid #e0e2e6;
  background: var(--bg-card); font-size: 0.85rem; cursor: pointer;
  color: var(--text-secondary); font-weight: 500; transition: all 0.2s;
}
.filter-bar button.active { background: var(--primary); color: white; border-color: var(--primary); }
.filter-bar button:hover:not(.active) { border-color: var(--primary); color: var(--primary); }

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: fixed; top: 60px; left: 0; right: 0;
    background: var(--bg-card); flex-direction: column;
    padding: 20px 24px; gap: 20px; border-bottom: 1px solid #eef0f2;
    box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  }
  .nav-menu.open { display: flex; }
  .nav-hamburger { display: flex; }
  .hero { padding: 70px 20px 50px; }
  .hero h1 { font-size: 1.6rem; }
  .hero p { font-size: 1rem; }
  .hero-stats { gap: 24px; }
  .cat-grid { grid-template-columns: repeat(2, 1fr); }
  .tool-grid { grid-template-columns: 1fr; }
  .collection-grid { grid-template-columns: 1fr; }
  .ad-mobile-bottom { display: block; }
  .section-title { font-size: 1.35rem; }
  .footer-links { flex-wrap: wrap; gap: 14px; }
}

@media (min-width: 769px) and (max-width: 1023px) {
  .cat-grid { grid-template-columns: repeat(3, 1fr); }
  .tool-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ===== Utility ===== */
.container { max-width: 1200px; margin: 0 auto; }