/* ===== Reset & Base ===== */
*, *::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", sans-serif; color: #1a1a2e; line-height: 1.6; background: #fff; }
a { color: inherit; text-decoration: none; }
img { max-width: 100%; }

/* ===== Container ===== */
.container { max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }

/* ===== Navbar ===== */
.navbar { position: fixed; top: 0; left: 0; right: 0; z-index: 1000; background: rgba(255,255,255,0.95); backdrop-filter: blur(12px); border-bottom: 1px solid #f0f0f0; }
.nav-inner { display: flex; align-items: center; height: 64px; gap: 1.5rem; }
.logo { font-size: 1.25rem; font-weight: 700; color: #1a5276; white-space: nowrap; }
.nav-links { display: flex; gap: 1.25rem; flex: 1; }
.nav-links a { font-size: 0.9rem; color: #555; transition: color 0.2s; white-space: nowrap; }
.nav-links a:hover { color: #1a5276; }
.nav-actions { display: flex; gap: 0.5rem; }
.nav-toggle { display: none; background: none; border: none; font-size: 1.5rem; cursor: pointer; }

/* ===== Buttons ===== */
.btn { display: inline-block; padding: 0.5rem 1.25rem; border-radius: 8px; font-size: 0.9rem; font-weight: 500; transition: all 0.2s; cursor: pointer; border: none; }
.btn-primary { background: #1a5276; color: #fff; }
.btn-primary:hover { background: #154360; }
.btn-outline { background: transparent; color: #1a5276; border: 1.5px solid #1a5276; }
.btn-outline:hover { background: #1a5276; color: #fff; }
.btn-sm { padding: 0.35rem 1rem; font-size: 0.85rem; }
.btn-lg { padding: 0.75rem 2rem; font-size: 1rem; }

/* ===== Hero ===== */
.hero { padding: 140px 0 80px; background: linear-gradient(135deg, #f8fbfd 0%, #e8f4f8 100%); text-align: center; }
.hero h1 { font-size: 2.75rem; font-weight: 800; margin-bottom: 1rem; line-height: 1.2; }
.highlight { color: #1a5276; }
.hero-sub { font-size: 1.2rem; color: #555; margin-bottom: 2rem; max-width: 600px; margin-left: auto; margin-right: auto; }
.hero-actions { display: flex; gap: 1rem; justify-content: center; }

/* ===== Sections ===== */
.section { padding: 80px 0; }
.section-alt { background: #f8fbfd; }
.section-title { text-align: center; font-size: 2rem; margin-bottom: 0.5rem; color: #1a5276; }
.section-desc { text-align: center; color: #777; margin-bottom: 2.5rem; }

/* ===== Grid ===== */
.grid { display: grid; gap: 1.5rem; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* ===== Cards ===== */
.card { background: #fff; border-radius: 12px; padding: 1.5rem; box-shadow: 0 2px 12px rgba(0,0,0,0.06); transition: transform 0.2s, box-shadow 0.2s; }
.card:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(0,0,0,0.1); }

/* ===== Capability Cards ===== */
.capability-card { text-align: center; }
.card-icon { font-size: 2.5rem; margin-bottom: 0.75rem; }
.capability-card h3 { margin-bottom: 0.5rem; color: #1a5276; }

/* ===== AI Demo ===== */
.ai-card h3 { color: #1a5276; margin-bottom: 1rem; }
.ai-demo-box { display: flex; flex-direction: column; gap: 0.5rem; }
.ai-input { background: #f5f5f5; padding: 0.75rem; border-radius: 8px; font-size: 0.85rem; color: #555; }
.ai-arrow { text-align: center; color: #1a5276; font-weight: bold; }
.ai-output { background: #e8f4f8; padding: 0.75rem; border-radius: 8px; font-size: 0.85rem; color: #1a5276; font-weight: 500; }

/* ===== Coming Soon ===== */
.coming-card { position: relative; text-align: center; }
.coming-badge { position: absolute; top: 1rem; right: 1rem; background: #f39c12; color: #fff; padding: 0.2rem 0.75rem; border-radius: 20px; font-size: 0.75rem; font-weight: 600; }
.coming-card h3 { margin-bottom: 0.5rem; color: #1a5276; }

/* ===== Pricing ===== */
.pricing-card { text-align: center; border: 2px solid #eee; }
.pricing-card.popular { border-color: #1a5276; position: relative; }
.pricing-card.popular::before { content: '推荐'; position: absolute; top: -12px; left: 50%; transform: translateX(-50%); background: #1a5276; color: #fff; padding: 0.15rem 1rem; border-radius: 20px; font-size: 0.8rem; font-weight: 600; }
.pricing-name { font-size: 1.2rem; font-weight: 700; color: #1a5276; margin-bottom: 0.5rem; }
.pricing-price { font-size: 2rem; font-weight: 800; color: #1a5276; margin-bottom: 0.25rem; }
.pricing-price span { font-size: 1rem; font-weight: 400; }
.pricing-desc { color: #888; font-size: 0.85rem; margin-bottom: 1rem; }
.pricing-features { list-style: none; margin-bottom: 1.5rem; }
.pricing-features li { padding: 0.3rem 0; font-size: 0.9rem; color: #555; }

/* ===== Trust ===== */
.trust-item { text-align: center; }
.trust-item h3 { color: #1a5276; margin-bottom: 0.5rem; }

/* ===== FAQ ===== */
.faq { max-width: 700px; margin: 0 auto; }
.faq-title { text-align: center; margin-bottom: 1.5rem; color: #1a5276; }
.faq-item { margin-bottom: 1rem; }
.faq-q { font-weight: 600; margin-bottom: 0.25rem; color: #333; }
.faq-a { color: #666; font-size: 0.9rem; padding-left: 1rem; }

/* ===== Footer ===== */
.footer { background: #1a1a2e; color: #aaa; padding: 2rem 0; text-align: center; font-size: 0.85rem; }

/* ===== Login / Register ===== */
.auth-page { min-height: 100vh; display: flex; align-items: center; justify-content: center; background: linear-gradient(135deg, #f8fbfd, #e8f4f8); }
.auth-box { background: #fff; padding: 2.5rem; border-radius: 16px; box-shadow: 0 4px 24px rgba(0,0,0,0.08); width: 100%; max-width: 420px; }
.auth-box h2 { text-align: center; color: #1a5276; margin-bottom: 0.5rem; }
.auth-box p { text-align: center; color: #888; margin-bottom: 1.5rem; font-size: 0.9rem; }
.form-group { margin-bottom: 1rem; }
.form-group label { display: block; font-size: 0.9rem; color: #555; margin-bottom: 0.25rem; }
.form-input { width: 100%; padding: 0.7rem 1rem; border: 1.5px solid #ddd; border-radius: 8px; font-size: 0.95rem; transition: border-color 0.2s; }
.form-input:focus { outline: none; border-color: #1a5276; }
.auth-submit { width: 100%; padding: 0.75rem; margin-top: 0.5rem; }
.auth-link { text-align: center; margin-top: 1rem; font-size: 0.85rem; color: #888; }
.auth-link a { color: #1a5276; font-weight: 500; }

/* ===== Material Card ===== */
.material-card { cursor: pointer; }
.material-card .cover { width: 100%; height: 180px; object-fit: cover; border-radius: 8px; margin-bottom: 0.75rem; background: #f0f0f0; }
.material-card h3 { font-size: 1rem; margin-bottom: 0.25rem; color: #1a1a2e; }
.material-card p { font-size: 0.85rem; color: #888; margin-bottom: 0.5rem; }
.material-card .tags { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.tag { display: inline-block; padding: 0.15rem 0.6rem; background: #e8f4f8; color: #1a5276; border-radius: 20px; font-size: 0.75rem; }

/* ===== Admin ===== */
.admin-layout { display: flex; min-height: 100vh; }
.admin-sidebar { width: 220px; background: #1a1a2e; color: #ccc; padding: 1.5rem 0; }
.admin-sidebar .logo { color: #fff; padding: 0 1.5rem; margin-bottom: 1.5rem; font-size: 1.1rem; }
.admin-nav a { display: block; padding: 0.6rem 1.5rem; color: #aaa; font-size: 0.9rem; transition: all 0.2s; }
.admin-nav a:hover, .admin-nav a.active { background: rgba(255,255,255,0.08); color: #fff; }
.admin-main { flex: 1; padding: 2rem; background: #f5f7fa; }
.admin-header { margin-bottom: 1.5rem; }
.admin-header h2 { color: #1a5276; }
.stat-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; margin-bottom: 2rem; }
.stat-card { background: #fff; padding: 1.25rem; border-radius: 10px; box-shadow: 0 1px 6px rgba(0,0,0,0.06); }
.stat-card .num { font-size: 1.75rem; font-weight: 700; color: #1a5276; }
.stat-card .label { font-size: 0.85rem; color: #888; margin-top: 0.25rem; }
.admin-table { width: 100%; border-collapse: collapse; background: #fff; border-radius: 10px; overflow: hidden; box-shadow: 0 1px 6px rgba(0,0,0,0.06); }
.admin-table th, .admin-table td { padding: 0.75rem 1rem; text-align: left; border-bottom: 1px solid #f0f0f0; font-size: 0.9rem; }
.admin-table th { background: #f8fbfd; color: #555; font-weight: 600; }

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .nav-links { display: none; }
  .nav-toggle { display: block; }
}
@media (max-width: 768px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.75rem; }
  .hero-sub { font-size: 1rem; }
  .stat-grid { grid-template-columns: repeat(2, 1fr); }
  .admin-sidebar { display: none; }
}