:root {
  --primary-color: #1a237e;
  --secondary-color: #4a148c;
  --accent-color: #ffab00;
  --tech-blue: #00bcd4;
  --tech-purple: #7b1fa2;
  --tech-neon: #00e676;
  --text-light: #f5f5f5;
  --text-dark: #212121;
  --bg-gradient: linear-gradient(135deg, #1a237e 0%, #4a148c 100%);
}

body {
  margin: 0;
  padding: 0;
  font-family: 'Roboto', 'Segoe UI', sans-serif;
  background: #f5f5f5;
  color: var(--text-dark);
  line-height: 1.6;
  font-size: 16px;
}

.header {
  position: relative;
  height: 600px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-gradient);
  color: var(--text-light);
  overflow: hidden;
  margin-bottom: 60px;
}

.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: 0.2;
}

.header-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  padding: 40px;
  text-align: center;
}

.header h1 {
  font-size: 3.5rem;
  margin-bottom: 20px;
  text-shadow: 0 4px 8px rgba(0,0,0,0.3);
}

.header p {
  font-size: 1.2rem;
  margin-bottom: 30px;
}

.note {
  position: fixed;
  top: 20px;
  right: 20px;
  background: rgba(255,255,255,0.9);
  color: var(--primary-color);
  padding: 10px 15px;
  border-radius: 20px;
  font-size: 14px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  z-index: 1000;
}

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

article {
  background: white;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.1);
  padding: 60px;
  margin-bottom: 80px;
}

h2 {
  color: var(--primary-color);
  font-size: 2.2rem;
  margin-top: 40px;
  margin-bottom: 30px;
  position: relative;
  padding-bottom: 15px;
}

h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 80px;
  height: 4px;
  background: var(--accent-color);
  border-radius: 2px;
}

h3 {
  color: var(--secondary-color);
  font-size: 1.8rem;
  margin-top: 35px;
  margin-bottom: 20px;
}

p {
  margin-bottom: 25px;
  font-size: 17px;
}

.img-container {
  display: flex;
  flex-wrap: wrap;
  gap: 30px;
  margin: 40px 0;
  justify-content: center;
}

.img-card {
  width: 300px;
  height: 300px;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

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

.img-card img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

pre {
  background: #2d2d2d;
  color: #f8f8f2;
  padding: 20px;
  border-radius: 8px;
  overflow-x: auto;
  margin: 30px 0;
  font-size: 15px;
  line-height: 1.5;
  box-shadow: inset 0 0 10px rgba(0,0,0,0.5);
}

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

.nav-links {
  position: sticky;
  top: 20px;
  margin-bottom: 40px;
  background: white;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.nav-links h3 {
  margin-top: 0;
  color: var(--tech-purple);
}

.nav-links ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.nav-links li {
  margin: 5px 0;
}

.nav-links a {
  display: block;
  padding: 8px 15px;
  background: #f0f0f0;
  color: var(--primary-color);
  text-decoration: none;
  border-radius: 20px;
  transition: all 0.3s ease;
}

.nav-links a:hover {
  background: var(--primary-color);
  color: white;
}

.footer {
  background: var(--primary-color);
  color: white;
  padding: 40px 0;
  text-align: center;
  margin-top: 80px;
}

.footer p {
  margin-bottom: 0;
}

@media (max-width: 768px) {
  .header {
    height: 500px;
  }
  
  .header h1 {
    font-size: 2.5rem;
  }
  
  article {
    padding: 30px;
  }
  
  h2 {
    font-size: 1.8rem;
  }
  
  h3 {
    font-size: 1.5rem;
  }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-15px); }
}

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