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

:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  --accent: #7c3aed;
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --success: #16a34a;
  --warning: #ea580c;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 30px rgba(0,0,0,0.08), 0 4px 12px rgba(0,0,0,0.04);
  --max-width: 1200px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

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

/* ========== Layout ========== */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }
.section { padding: 64px 0; }
.section-sm { padding: 40px 0; }

/* ========== Header ========== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.logo {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
}
.logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.85rem;
  font-weight: 800;
}
.nav { display: flex; align-items: center; gap: 32px; }
.nav a { color: var(--text-secondary); font-weight: 500; font-size: 0.95rem; }
.nav a:hover { color: var(--primary); }
.lang-toggle {
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s;
  background: white;
}
.lang-toggle:hover { border-color: var(--primary); color: var(--primary); }

/* ========== Hero ========== */
.hero {
  background: linear-gradient(135deg, #eff6ff 0%, #f5f3ff 100%);
  padding: 80px 0 64px;
  text-align: center;
}
.hero h1 {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto 32px;
}
.hero-stats {
  display: flex;
  justify-content: center;
  gap: 48px;
  margin-top: 40px;
  flex-wrap: wrap;
}
.hero-stat { text-align: center; }
.hero-stat .num { font-size: 2rem; font-weight: 800; color: var(--primary); }
.hero-stat .label { font-size: 0.85rem; color: var(--text-secondary); }

/* ========== Buttons ========== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
  text-decoration: none;
}
.btn-primary {
  background: var(--primary);
  color: white;
}
.btn-primary:hover { background: var(--primary-dark); color: white; transform: translateY(-1px); box-shadow: var(--shadow-lg); }
.btn-outline {
  background: white;
  color: var(--primary);
  border: 1px solid var(--primary);
}
.btn-outline:hover { background: var(--primary-light); }
.btn-lg { padding: 16px 36px; font-size: 1.05rem; }

/* ========== Section Title ========== */
.section-title {
  text-align: center;
  margin-bottom: 48px;
}
.section-title h2 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 12px;
}
.section-title p {
  color: var(--text-secondary);
  font-size: 1.05rem;
}

/* ========== Model Cards ========== */
.model-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}
.model-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: all 0.3s;
  position: relative;
}
.model-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
  border-color: var(--primary);
}
.model-card .badge {
  position: absolute;
  top: 16px;
  right: 16px;
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 600;
}
.badge-best { background: #fef3c7; color: #92400e; }
.badge-flagship { background: #ede9fe; color: #5b21b6; }
.badge-cheap { background: #d1fae5; color: #065f46; }
.model-card h3 { font-size: 1.25rem; font-weight: 700; margin-bottom: 8px; }
.model-card .provider { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 16px; }
.model-card .price {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary);
}
.model-card .price-unit { font-size: 0.85rem; color: var(--text-secondary); font-weight: 400; }
.model-card .features { margin: 16px 0; padding: 0; list-style: none; }
.model-card .features li {
  padding: 4px 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 8px;
}
.model-card .features li::before { content: "✓"; color: var(--success); font-weight: 700; }

/* ========== Comparison Table ========== */
.comparison-table-wrap {
  overflow-x: auto;
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}
.comparison-table th {
  background: #f1f5f9;
  padding: 16px 20px;
  text-align: left;
  font-weight: 700;
  color: var(--text);
  border-bottom: 2px solid var(--border);
  white-space: nowrap;
}
.comparison-table td {
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}
.comparison-table tr:last-child td { border-bottom: none; }
.comparison-table tr:hover { background: #f8fafc; }
.comparison-table .price-cell { font-weight: 700; color: var(--primary); }
.comparison-table .model-name { font-weight: 600; color: var(--text); }

/* ========== Article List ========== */
.article-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
}
.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: all 0.3s;
  display: flex;
  flex-direction: column;
}
.article-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  border-color: var(--primary);
}
.article-card .tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--primary-light);
  color: var(--primary);
  margin-bottom: 12px;
  align-self: flex-start;
}
.article-card h3 { font-size: 1.15rem; font-weight: 700; margin-bottom: 8px; line-height: 1.4; }
.article-card p { font-size: 0.9rem; color: var(--text-secondary); flex: 1; }
.article-card .read-more { margin-top: 16px; font-size: 0.9rem; font-weight: 600; }

/* ========== Calculator ========== */
.calculator {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow);
  max-width: 800px;
  margin: 0 auto;
}
.calc-input-group { margin-bottom: 24px; }
.calc-input-group label { display: block; font-weight: 600; margin-bottom: 8px; }
.calc-input-group input[type="range"] { width: 100%; accent-color: var(--primary); }
.calc-input-group .value-display { font-size: 1.5rem; font-weight: 800; color: var(--primary); }
.calc-result {
  margin-top: 32px;
  border-top: 1px solid var(--border);
  padding-top: 24px;
}
.calc-result-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
}
.calc-result-row:last-child { border-bottom: none; }
.calc-result-row .model { font-weight: 600; }
.calc-result-row .cost { font-weight: 700; font-size: 1.1rem; }
.calc-result-row .cost.cheapest { color: var(--success); }
.calc-result-row .badge-cheap {
  font-size: 0.7rem;
  padding: 2px 8px;
  border-radius: 4px;
  background: #d1fae5;
  color: #065f46;
  margin-left: 8px;
}

/* ========== Article Page ========== */
.article-body {
  max-width: 760px;
  margin: 0 auto;
}
.article-body h1 { font-size: 2.25rem; font-weight: 800; margin-bottom: 16px; line-height: 1.3; }
.article-meta { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 32px; display: flex; gap: 16px; align-items: center; }
.article-body h2 { font-size: 1.5rem; font-weight: 700; margin: 40px 0 16px; }
.article-body h3 { font-size: 1.2rem; font-weight: 600; margin: 28px 0 12px; }
.article-body p { margin-bottom: 16px; color: var(--text); }
.article-body ul, .article-body ol { margin: 16px 0 16px 24px; }
.article-body li { margin-bottom: 8px; }
.article-body blockquote {
  border-left: 4px solid var(--primary);
  background: var(--primary-light);
  padding: 16px 24px;
  border-radius: 0 8px 8px 0;
  margin: 24px 0;
}
.article-body code {
  background: #f1f5f9;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
  font-family: "SF Mono", "Fira Code", "Consolas", monospace;
}
.article-body pre {
  background: #1e293b;
  color: #e2e8f0;
  padding: 24px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 24px 0;
}
.article-body pre code { background: none; padding: 0; color: inherit; }
.article-cta {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: white;
  border-radius: var(--radius);
  padding: 32px;
  margin: 40px 0;
  text-align: center;
}
.article-cta h3 { color: white; margin-bottom: 8px; }
.article-cta p { color: rgba(255,255,255,0.9); margin-bottom: 20px; }
.article-cta .btn { background: white; color: var(--primary); }
.article-cta .btn:hover { transform: translateY(-2px); }

/* ========== Footer ========== */
.footer {
  background: #1e293b;
  color: #94a3b8;
  padding: 48px 0 32px;
  margin-top: 64px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 32px;
  margin-bottom: 32px;
}
.footer-brand h4 { color: white; font-size: 1.1rem; margin-bottom: 12px; }
.footer-brand p { font-size: 0.9rem; line-height: 1.6; }
.footer-col h5 { color: white; font-size: 0.9rem; margin-bottom: 12px; }
.footer-col a { display: block; color: #94a3b8; font-size: 0.9rem; margin-bottom: 8px; }
.footer-col a:hover { color: white; }
.footer-bottom {
  border-top: 1px solid #334155;
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
  .hero h1 { font-size: 2rem; }
  .hero p { font-size: 1rem; }
  .hero-stats { gap: 24px; }
  .nav { gap: 16px; }
  .nav a:not(.lang-toggle) { display: none; }
  .footer-grid { grid-template-columns: 1fr; gap: 24px; }
  .section-title h2 { font-size: 1.5rem; }
  .calculator { padding: 24px; }
  .article-body h1 { font-size: 1.75rem; }
}