:root {
  --primary-dark: #1E3A8A;
  --primary-light: #3B82F6;
  --secondary-dark: #1F2937;
  --secondary-light: #E5E7EB;
  --accent: #10B981;
  --text-primary: #111827;
  --text-secondary: #6B7280;
  --bg-light: #F9FAFB;
}

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

body {
  font-family: 'Roboto', sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-light);
  overflow-x: hidden;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: linear-gradient(135deg, var(--primary-dark), var(--primary-light));
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
  z-index: 1000;
  padding: 15px 0;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: white;
  text-decoration: none;
}

.nav-menu {
  display: flex;
  gap: 30px;
}

.nav-link {
  color: white;
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s ease;
  position: relative;
}

.nav-link:hover {
  color: var(--accent);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--accent);
  transition: width 0.3s ease;
}

.nav-link:hover::after {
  width: 100%;
}

.hero {
  height: 600px;
  display: flex;
  align-items: center;
  background: linear-gradient(rgba(30, 58, 138, 0.8), rgba(30, 58, 138, 0.8)), url('https://images.gptkong.com/demo/sample1.png');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  color: white;
  margin-top: 60px;
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 100px;
  background: linear-gradient(transparent, var(--bg-light));
}

.hero-content {
  max-width: 800px;
}

.hero-title {
  font-size: 3rem;
  margin-bottom: 20px;
  line-height: 1.2;
}

.hero-subtitle {
  font-size: 1.2rem;
  margin-bottom: 30px;
  opacity: 0.9;
}

.notice {
  background-color: var(--accent);
  color: white;
  padding: 15px;
  text-align: center;
  font-weight: 500;
  margin-bottom: 40px;
}

.content-section {
  padding: 80px 0;
}

.section-title {
  font-size: 2.2rem;
  margin-bottom: 40px;
  color: var(--primary-dark);
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 50%;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-light), var(--accent));
}

.article {
  background-color: white;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
  padding: 40px;
  margin-bottom: 40px;
}

.article h2 {
  font-size: 1.8rem;
  color: var(--primary-dark);
  margin-bottom: 20px;
}

.article h3 {
  font-size: 1.4rem;
  color: var(--primary-light);
  margin: 30px 0 15px;
}

.article p {
  margin-bottom: 20px;
  color: var(--text-primary);
  font-size: 1.1rem;
}

.article strong {
  color: var(--primary-dark);
}

.article span[style*="color"] {
  font-weight: 600;
}

.code-block {
  background-color: var(--secondary-dark);
  color: white;
  padding: 20px;
  border-radius: 8px;
  margin: 20px 0;
  overflow-x: auto;
  font-family: 'Courier New', monospace;
  position: relative;
}

.code-block::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: linear-gradient(to bottom, var(--accent), var(--primary-light));
}

pre {
  margin: 0;
}

code {
  font-family: 'Courier New', monospace;
  font-size: 0.9rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 30px 0;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

th, td {
  padding: 15px;
  text-align: left;
  border-bottom: 1px solid var(--secondary-light);
}

th {
  background-color: var(--primary-dark);
  color: white;
}

tr:nth-child(even) {
  background-color: var(--bg-light);
}

tr:hover {
  background-color: rgba(59, 130, 246, 0.1);
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin: 40px 0;
}

.image-card {
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.image-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.image-card img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform 0.5s ease;
}

.image-card:hover img {
  transform: scale(1.05);
}

.footer {
  background: linear-gradient(135deg, var(--primary-dark), var(--secondary-dark));
  color: white;
  padding: 50px 0;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 30px;
  margin-bottom: 30px;
}

.footer-link {
  color: white;
  text-decoration: none;
  transition: color 0.3s ease;
}

.footer-link:hover {
  color: var(--accent);
}

.copyright {
  opacity: 0.7;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .nav-menu {
    gap: 15px;
  }
  
  .hero-title {
    font-size: 2.2rem;
  }
  
  .hero-subtitle {
    font-size: 1rem;
  }
  
  .section-title {
    font-size: 1.8rem;
  }
  
  .article {
    padding: 30px;
  }
  
  .image-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 576px) {
  .nav {
    flex-direction: column;
    gap: 15px;
  }
  
  .hero {
    height: 500px;
    text-align: center;
  }
  
  .hero-title {
    font-size: 1.8rem;
  }
  
  .footer-links {
    flex-direction: column;
    gap: 15px;
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate {
  animation: fadeIn 1s ease-out forwards;
}

.delay-1 {
  animation-delay: 0.2s;
}

.delay-2 {
  animation-delay: 0.4s;
}

.delay-3 {
  animation-delay: 0.6s;
}