:root {
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --bg-dark: #0a0c10;
  --bg-card: #11141d;
  --bg-card-hover: #1a1e2b;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-glow: rgba(59, 130, 246, 0.5);
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
  --glass-bg: rgba(17, 20, 29, 0.7);
  --glass-border: rgba(255, 255, 255, 0.1);
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  background-image: 
    radial-gradient(circle at 15% 50%, rgba(59, 130, 246, 0.08), transparent 25%),
    radial-gradient(circle at 85% 30%, rgba(59, 130, 246, 0.08), transparent 25%);
}

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

/* Typography */
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
}

.text-gradient {
  background: linear-gradient(135deg, #60a5fa, #3b82f6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Header & Nav */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  padding: 1.5rem 0;
  background: rgba(10, 12, 16, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: all 0.3s ease;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--primary-color), #8b5cf6);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
}

.nav-links {
  display: flex;
  gap: 2.5rem;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.3s ease;
}

.nav-links a:hover {
  color: var(--text-main);
}

.nav-actions {
  display: flex;
  gap: 1rem;
  align-items: center;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.3s ease;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--primary-color);
  color: white;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.4);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.5);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
}

/* Hero Section */
.hero {
  padding: 12rem 2rem 6rem;
  text-align: center;
  max-width: 900px;
  margin: 0 auto;
  position: relative;
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  letter-spacing: -1px;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  max-width: 700px;
  margin-inline: auto;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 4rem;
  margin-top: 4rem;
  padding-top: 3rem;
  border-top: 1px solid var(--border-color);
}

.stat-item h4 {
  font-size: 2rem;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

.stat-item p {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin: 0;
}

/* Sections */
.section-title {
  text-align: center;
  margin-bottom: 4rem;
}

.section-title h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.section-title p {
  color: var(--text-muted);
  font-size: 1.1rem;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 6rem 2rem;
}

/* Pricing */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 2.5rem 2rem;
  transition: all 0.4s ease;
  position: relative;
  display: flex;
  flex-direction: column;
}

.pricing-card:hover {
  transform: translateY(-5px);
  background: var(--bg-card-hover);
  border-color: rgba(255,255,255,0.2);
  box-shadow: 0 10px 40px rgba(0,0,0,0.5);
}

.pricing-card.popular {
  border-color: var(--primary-color);
  box-shadow: 0 0 20px rgba(59, 130, 246, 0.15);
}

.pricing-card.popular::before {
  content: '热门';
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: var(--primary-color);
  color: white;
  font-size: 0.75rem;
  font-weight: bold;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
}

.pricing-header {
  margin-bottom: 2rem;
}

.pricing-header h3 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.pricing-features {
  list-style: none;
  margin-bottom: 2.5rem;
  flex-grow: 1;
}

.pricing-features li {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.pricing-features li svg {
  color: var(--primary-color);
  flex-shrink: 0;
}

.pricing-card .btn {
  width: 100%;
}

/* Reviews */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.review-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(10px);
  padding: 2rem;
  border-radius: 16px;
}

.review-text {
  font-size: 1rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  font-style: italic;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.review-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--primary-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  color: white;
}

.review-info h4 {
  font-size: 1rem;
  margin: 0;
}

.review-info p {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin: 0;
}

/* FAQ */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  margin-bottom: 1rem;
  overflow: hidden;
}

.faq-question {
  padding: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  font-weight: 600;
  font-size: 1.1rem;
  transition: background 0.3s ease;
}

.faq-question:hover {
  background: var(--bg-card-hover);
}

.faq-answer {
  padding: 0 1.5rem;
  max-height: 0;
  overflow: hidden;
  transition: all 0.3s ease;
  color: var(--text-muted);
}

.faq-item.active .faq-answer {
  padding: 0 1.5rem 1.5rem;
  max-height: 300px;
}

.faq-icon {
  transition: transform 0.3s ease;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

/* Articles Section */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.5rem;
  transition: transform 0.3s ease;
}

.article-card:hover {
  transform: translateY(-5px);
  border-color: rgba(255,255,255,0.2);
}

.article-card h3 {
  font-size: 1.25rem;
  margin-bottom: 1rem;
}

.article-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1.5rem;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.article-link {
  color: var(--primary-color);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

/* Footer */
footer {
  border-top: 1px solid var(--border-color);
  padding: 4rem 2rem 2rem;
  background: #050608;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 3rem;
  margin-bottom: 4rem;
}

.footer-col h4 {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
}

.footer-col ul {
  list-style: none;
}

.footer-col ul li {
  margin-bottom: 0.75rem;
}

.footer-col a {
  color: var(--text-muted);
  font-size: 0.95rem;
  transition: color 0.3s;
}

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

.footer-bottom {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  border-top: 1px solid rgba(255,255,255,0.05);
  padding-top: 2rem;
}

/* Mobile Responsive */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  
  .hero h1 {
    font-size: 2.5rem;
  }
  
  .hero-stats {
    flex-direction: column;
    gap: 2rem;
  }
  
  .container {
    padding: 4rem 1.5rem;
  }
}