:root {
  --primary-color: #0D47A1;
  --secondary-color: #B0BEC5;
  --accent-color: #FF6F00;
  --background-gradient: linear-gradient(135deg, #f5f7fa 0%, #e4e8eb 100%);
  --card-shadow: 0 10px 30px -15px rgba(0,0,0,0.2);
  --text-primary: #2d3748;
  --text-secondary: #4a5568;
}

@font-face {
  font-family: 'Roboto';
  src: url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500;700&display=swap');
}

@font-face {
  font-family: 'Open Sans';
  src: url('https://fonts.googleapis.com/css2?family=Open+Sans:wght@300;400;600;700&display=swap');
}

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

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

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

.header {
  position: relative;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 40px;
  background: rgba(13, 71, 161, 0.9);
  backdrop-filter: blur(10px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  z-index: 1000;
}

.logo {
  font-family: 'Roboto', sans-serif;
  font-weight: 700;
  font-size: 24px;
  color: white;
  text-decoration: none;
  letter-spacing: 1px;
}

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

.nav-links a {
  color: white;
  text-decoration: none;
  font-family: 'Roboto', sans-serif;
  font-weight: 500;
  font-size: 16px;
  position: relative;
  transition: all 0.3s ease;
}

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

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

.hero {
  position: relative;
  height: 500px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: linear-gradient(135deg, rgba(13,71,161,0.8) 0%, rgba(0,105,192,0.8) 100%);
  color: white;
  overflow: hidden;
  margin-bottom: 80px;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('https://images.gptkong.com/demo/sample1.png') center/cover no-repeat;
  opacity: 0.1;
  z-index: -1;
}

.hero-content {
  max-width: 800px;
  padding: 0 20px;
  z-index: 1;
}

.hero h1 {
  font-size: 48px;
  font-weight: 700;
  margin-bottom: 20px;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.hero p {
  font-size: 20px;
  margin-bottom: 30px;
  opacity: 0.9;
}

.notice {
  background: rgba(255,255,255,0.2);
  backdrop-filter: blur(5px);
  padding: 15px 25px;
  border-radius: 8px;
  display: inline-block;
  margin-top: 30px;
  font-size: 14px;
  border: 1px solid rgba(255,255,255,0.3);
}

article {
  max-width: 900px;
  margin: 0 auto 80px;
  background: white;
  border-radius: 12px;
  box-shadow: var(--card-shadow);
  padding: 60px;
  position: relative;
  overflow: hidden;
}

article::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 5px;
  height: 100%;
  background: linear-gradient(to bottom, var(--primary-color), var(--accent-color));
}

article h2 {
  font-family: 'Roboto', sans-serif;
  font-size: 32px;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 30px;
  position: relative;
  padding-bottom: 15px;
}

article h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 3px;
  background: var(--accent-color);
}

article h3 {
  font-family: 'Roboto', sans-serif;
  font-size: 24px;
  font-weight: 600;
  color: var(--primary-color);
  margin: 40px 0 20px;
}

article p {
  font-size: 17px;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 25px;
}

pre {
  background: #f8f9fa;
  border-radius: 8px;
  padding: 20px;
  margin: 30px 0;
  overflow: auto;
  border-left: 4px solid var(--accent-color);
}

code {
  font-family: 'Courier New', monospace;
  font-size: 14px;
  color: #333;
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin: 40px 0;
}

.image-card {
  position: relative;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.image-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 15px 30px rgba(0,0,0,0.2);
}

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

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

.footer {
  background: var(--primary-color);
  color: white;
  padding: 40px 0;
  text-align: center;
}

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

.footer p {
  margin-bottom: 20px;
  opacity: 0.8;
}

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

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

.footer-links a:hover {
  opacity: 0.7;
}

@media (max-width: 768px) {
  .hero h1 {
    font-size: 36px;
  }
  
  article {
    padding: 40px;
  }
  
  article h2 {
    font-size: 28px;
  }
  
  .image-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .header {
    padding: 0 20px;
  }
  
  .nav-links {
    gap: 15px;
  }
  
  .hero h1 {
    font-size: 28px;
  }
  
  article {
    padding: 30px 20px;
  }
  
  article h2 {
    font-size: 24px;
  }
}