:root {
  --primary-color: #0D47A1;
  --secondary-color: #37474F;
  --accent-color: #00C853;
  --background-color: #FFFFFF;
  --light-gray: #F5F5F5;
  --dark-blue: #0a3a7a;
  --gradient-blue: linear-gradient(135deg, #0D47A1 0%, #1976D2 100%);
  --gradient-green: linear-gradient(135deg, #00C853 0%, #64DD17 100%);
}

body {
  margin: 0;
  padding: 0;
  background-color: var(--background-color);
  color: var(--secondary-color);
  font-family: 'Open Sans', sans-serif;
  line-height: 1.6;
  overflow-x: hidden;
}

.header {
  background: var(--gradient-blue);
  color: white;
  padding: 6rem 2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.header::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: 0;
}

.header-content {
  position: relative;
  z-index: 1;
  max-width: 1200px;
  margin: 0 auto;
}

.header h1 {
  font-size: 3rem;
  margin-bottom: 1.5rem;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.header p {
  font-size: 1.2rem;
  max-width: 800px;
  margin: 0 auto 2rem;
}

.notice {
  background-color: rgba(255,255,255,0.2);
  padding: 1rem;
  border-radius: 8px;
  display: inline-block;
  margin-top: 2rem;
  backdrop-filter: blur(5px);
}

.container {
  max-width: 1200px;
  margin: 3rem auto;
  padding: 0 2rem;
}

article {
  background-color: white;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.05);
  padding: 3rem;
  margin-bottom: 3rem;
}

article h2 {
  color: var(--primary-color);
  font-size: 2rem;
  margin-bottom: 2rem;
  position: relative;
  padding-bottom: 1rem;
}

article h2::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100px;
  height: 4px;
  background: var(--gradient-green);
  border-radius: 2px;
}

article h3 {
  color: var(--dark-blue);
  font-size: 1.5rem;
  margin: 2rem 0 1.5rem;
}

article p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin: 3rem 0;
}

.image-card {
  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(-5px);
  box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.image-card img {
  width: 100%;
  height: auto;
  display: block;
}

pre {
  background-color: #f8f9fa;
  border-radius: 8px;
  padding: 1.5rem;
  overflow: auto;
  margin: 2rem 0;
  border-left: 4px solid var(--accent-color);
  font-size: 0.95rem;
}

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

.nav-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin: 3rem 0;
}

.nav-link {
  padding: 0.8rem 1.5rem;
  background: var(--gradient-blue);
  color: white;
  border-radius: 50px;
  text-decoration: none;
  font-weight: bold;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.nav-link:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(0,0,0,0.15);
}

.footer {
  background: var(--gradient-blue);
  color: white;
  text-align: center;
  padding: 2rem;
  margin-top: 3rem;
}

@media (max-width: 768px) {
  .header {
    padding: 4rem 1rem;
  }
  
  .header h1 {
    font-size: 2.2rem;
  }
  
  article {
    padding: 2rem;
  }
  
  .image-grid {
    grid-template-columns: 1fr;
  }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

.floating {
  animation: float 3s ease-in-out infinite;
}

.highlight-box {
  background: rgba(13, 71, 161, 0.05);
  border-left: 4px solid var(--primary-color);
  padding: 1.5rem;
  margin: 2rem 0;
  border-radius: 0 8px 8px 0;
}

.highlight-box h4 {
  color: var(--primary-color);
  margin-top: 0;
}