:root {
  --c-primary: #4f46e5;
  --c-primary-dark: #3730a3;
  --c-primary-light: #818cf8;
  --c-accent: #06b6d4;
  --c-accent-dark: #0891b2;
  --c-bg: #f0f2f5;
  --c-bg-card: #ffffff;
  --c-text: #1e293b;
  --c-text-secondary: #64748b;
  --c-text-muted: #94a3b8;
  --c-border: #e2e8f0;
  --radius: 14px;
  --radius-sm: 10px;
  --shadow-card: 0 1px 3px rgba(0,0,0,.06), 0 1px 2px rgba(0,0,0,.04);
  --shadow-card-hover: 0 10px 25px rgba(0,0,0,.1), 0 4px 10px rgba(0,0,0,.05);
  --shadow-nav: 0 1px 3px rgba(0,0,0,.08);
  --transition: 0.2s ease;
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
  padding: 0;
  margin: -1px;
}

.container { max-width: 1320px; margin: 0 auto; padding: 0 24px; }

.header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.92); backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--c-border);
  padding: 0;
}

.header-inner {
  display: flex; align-items: center; gap: 20px;
  height: 64px;
}

.logo {
  display: flex; align-items: center; gap: 10px;
  flex-shrink: 0;
}

.logo-icon {
  width: 38px; height: 38px;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: #fff;
}

.logo-icon svg { width: 20px; height: 20px; }

.logo-text {
  font-size: 1.25rem; font-weight: 700;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}

.search-box {
  flex: 1; max-width: 420px; position: relative;
}

.search-box .fa-search {
  position: absolute; left: 14px; top: 50%; transform: translateY(-50%);
  color: var(--c-text-muted); font-size: 15px; pointer-events: none;
}

.search-input {
  width: 100%; height: 42px; padding: 0 16px 0 40px;
  border: 1.5px solid var(--c-border); border-radius: 21px;
  font-size: .9rem; background: var(--c-bg); color: var(--c-text);
  transition: all var(--transition); outline: none;
}

.search-input:focus {
  border-color: var(--c-primary); background: #fff;
  box-shadow: 0 0 0 3px rgba(79,70,229,.1);
}

.search-input::placeholder { color: var(--c-text-muted); }

.stats-badge {
  display: flex; align-items: center; gap: 6px;
  flex-shrink: 0;
  padding: 6px 14px; border-radius: 20px;
  background: linear-gradient(135deg, rgba(79,70,229,.08), rgba(6,182,212,.08));
  font-size: .8rem; font-weight: 600; color: var(--c-primary);
}

.stats-badge .count { font-size: 1.1rem; }

.category-bar {
  padding: 20px 0 8px;
  overflow-x: auto;
  white-space: nowrap;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.category-bar::-webkit-scrollbar { display: none; }

.category-list {
  display: inline-flex; gap: 10px;
  padding: 0 2px;
}

.cat-btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 9px 18px; border-radius: 22px;
  border: 1.5px solid var(--c-border);
  background: #fff; color: var(--c-text-secondary);
  font-size: .875rem; font-weight: 500; cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.cat-btn:hover { border-color: var(--c-primary-light); color: var(--c-primary); }

.cat-btn.active {
  background: var(--c-primary); color: #fff; border-color: var(--c-primary);
  box-shadow: 0 4px 12px rgba(79,70,229,.3);
}

.cat-btn .fa { font-size: 14px; }

.tools-section { padding: 12px 0 60px; }

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 18px;
}

.tool-card {
  display: flex; flex-direction: column;
  padding: 20px 22px;
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.tool-card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
  opacity: 0; transition: opacity var(--transition);
}

.tool-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-card-hover);
  border-color: var(--c-primary-light);
}

.tool-card:hover::before { opacity: 1; }

.tool-card-header {
  display: flex; align-items: flex-start; gap: 14px;
  margin-bottom: 12px;
}

.tool-avatar {
  width: 44px; height: 44px; flex-shrink: 0;
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, #eef2ff, #ecfeff);
  color: var(--c-primary);
  font-size: 20px;
}

.tool-info { flex: 1; min-width: 0; }

.tool-name {
  font-size: 1rem; font-weight: 600; color: var(--c-text);
  line-height: 1.3; margin-bottom: 2px;
}

.tool-cat {
  font-size: .72rem; color: var(--c-primary);
  font-weight: 500; opacity: .8;
}

.tool-desc {
  flex: 1;
  font-size: .85rem; color: var(--c-text-secondary);
  line-height: 1.55;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 14px;
}

.tool-card-footer {
  display: flex; align-items: center; justify-content: space-between;
  padding-top: 12px; border-top: 1px solid var(--c-border);
}

.tool-tag {
  font-size: .72rem; color: var(--c-text-muted);
  background: var(--c-bg); padding: 3px 10px; border-radius: 20px;
}

.tool-arrow {
  display: flex; align-items: center; gap: 4px;
  font-size: .8rem; color: var(--c-primary);
  font-weight: 500; transition: gap var(--transition);
}

.tool-card:hover .tool-arrow { gap: 8px; }

.empty-state {
  grid-column: 1 / -1;
  display: flex; flex-direction: column; align-items: center;
  padding: 80px 20px; text-align: center;
}

.empty-state .fa {
  font-size: 48px; color: var(--c-text-muted); margin-bottom: 20px;
}

.empty-state h3 { font-size: 1.1rem; color: var(--c-text); margin-bottom: 8px; }

.empty-state p { font-size: .9rem; color: var(--c-text-secondary); }

.footer {
  background: #fff; border-top: 1px solid var(--c-border);
  padding: 32px 0; text-align: center;
}

.footer-inner {
  display: flex; flex-direction: column; align-items: center; gap: 12px;
}

.footer-brand {
  display: flex; align-items: center; gap: 8px;
  font-size: 1rem; font-weight: 600; color: var(--c-text);
}

.footer-brand .fa { color: var(--c-primary); font-size: 18px; }

.footer-desc { font-size: .85rem; color: var(--c-text-secondary); }

.footer-links { display: flex; gap: 24px; margin-top: 4px; }

.footer-links a { font-size: .85rem; color: var(--c-text-secondary); transition: color var(--transition); }

.footer-links a:hover { color: var(--c-primary); }

.footer-copy { font-size: .75rem; color: var(--c-text-muted); margin-top: 8px; }

.back-to-top {
  position: fixed; bottom: 32px; right: 32px;
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--c-primary); color: #fff; border: none;
  cursor: pointer; font-size: 18px;
  box-shadow: 0 4px 14px rgba(79,70,229,.35);
  opacity: 0; visibility: hidden;
  transform: translateY(10px);
  transition: all .3s ease;
  z-index: 90;
  display: flex; align-items: center; justify-content: center;
}

.back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }

.back-to-top:hover { background: var(--c-primary-dark); transform: translateY(-2px); }

.back-to-top.show:hover { transform: translateY(-2px); }

.cat-btn:focus-visible,
.search-input:focus-visible,
.back-to-top:focus-visible {
  outline: 2px solid var(--c-primary);
  outline-offset: 2px;
}

.tool-card:focus-visible {
  outline: 2px solid var(--c-primary);
  outline-offset: 2px;
  border-color: var(--c-primary);
}

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

.tool-card { animation: fadeInUp .35s ease backwards; }

@media (max-width: 1024px) {
  .tools-grid { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; }
}

@media (max-width: 768px) {
  .container { padding: 0 16px; }
  .header-inner { flex-wrap: wrap; height: auto; padding: 12px 0; }
  .search-box { order: 3; max-width: 100%; width: 100%; flex-basis: 100%; }
  .tools-grid { grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 12px; }
  .tool-card { padding: 16px 18px; }
  .category-bar { padding: 14px 0 6px; }
  .cat-btn { padding: 7px 14px; font-size: .8rem; }
}

@media (max-width: 480px) {
  .tools-grid { grid-template-columns: 1fr; }
  .logo-text { font-size: 1.1rem; }
  .logo-icon { width: 32px; height: 32px; border-radius: 8px; }
  .stats-badge { display: none; }
  .back-to-top { bottom: 20px; right: 20px; width: 40px; height: 40px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .tool-card { animation: none; }
  .tool-card:hover,
  .back-to-top:hover,
  .back-to-top.show:hover { transform: none; }
  * { transition: none !important; }
}