:root {
  --primary: #0D47A1;
  --secondary: #29B6F6;
  --accent: #FFC107;
  --light: #FFFFFF;
  --dark: #333333;
  --gray: #F5F5F5;
}

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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--dark);
  background-color: var(--gray);
  padding: 0;
  margin: 0;
}

.header {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--light);
  padding: 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') no-repeat right center;
  background-size: contain;
  opacity: 0.2;
}

.header h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  position: relative;
  z-index: 1;
  text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.header p {
  font-size: 1.2rem;
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.notice {
  background-color: var(--accent);
  color: var(--dark);
  padding: 1rem;
  text-align: center;
  font-weight: bold;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.main-container {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 2rem;
  max-width: 1400px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.sidebar {
  background: var(--light);
  border-radius: 8px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  padding: 1.5rem;
  position: sticky;
  top: 1rem;
  height: fit-content;
}

.sidebar h3 {
  color: var(--primary);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--secondary);
}

.nav-links {
  list-style: none;
}

.nav-links li {
  margin-bottom: 0.5rem;
}

.nav-links a {
  display: block;
  padding: 0.8rem 1rem;
  color: var(--dark);
  text-decoration: none;
  border-radius: 4px;
  transition: all 0.3s ease;
  position: relative;
}

.nav-links a::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  width: 3px;
  height: 100%;
  background: var(--secondary);
  transform: scaleY(0);
  transition: transform 0.3s;
}

.nav-links a:hover {
  background: rgba(41, 182, 246, 0.1);
  color: var(--primary);
}

.nav-links a:hover::before {
  transform: scaleY(1);
}

.content {
  background: var(--light);
  border-radius: 8px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  padding: 2rem;
}

.article-section {
  margin-bottom: 3rem;
  position: relative;
}

.article-section::after {
  content: '';
  display: block;
  height: 1px;
  background: linear-gradient(to right, transparent, var(--secondary), transparent);
  margin-top: 2rem;
}

.article-section h2 {
  color: var(--primary);
  font-size: 1.8rem;
  margin-bottom: 1.5rem;
  position: relative;
  display: inline-block;
}

.article-section h2::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 60%;
  height: 3px;
  background: var(--accent);
  border-radius: 3px;
}

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

.highlight {
  color: var(--accent);
  font-weight: bold;
}

.code-block {
  background: #282c34;
  color: #abb2bf;
  padding: 1.5rem;
  border-radius: 8px;
  margin: 1.5rem 0;
  overflow-x: auto;
  font-family: 'Courier New', Courier, monospace;
  font-size: 0.95rem;
  line-height: 1.5;
  box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}

.code-block::-webkit-scrollbar {
  height: 6px;
}

.code-block::-webkit-scrollbar-thumb {
  background: var(--secondary);
  border-radius: 3px;
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.image-card {
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 15px rgba(0,0,0,0.1);
  transition: transform 0.3s, box-shadow 0.3s;
}

.image-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

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

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

.footer {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--light);
  text-align: center;
  padding: 2rem;
  margin-top: 3rem;
}

.footer p {
  max-width: 800px;
  margin: 0 auto;
}

@media (max-width: 1024px) {
  .main-container {
    grid-template-columns: 1fr;
  }
  
  .sidebar {
    position: static;
    margin-bottom: 2rem;
  }
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2rem;
  }
  
  .article-section h2 {
    font-size: 1.5rem;
  }
  
  .image-grid {
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  }
}

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

.article-section {
  animation: fadeIn 0.6s ease-out forwards;
}

.article-section:nth-child(2) { animation-delay: 0.1s; }
.article-section:nth-child(3) { animation-delay: 0.2s; }
.article-section:nth-child(4) { animation-delay: 0.3s; }
.article-section:nth-child(5) { animation-delay: 0.4s; }
.article-section:nth-child(6) { animation-delay: 0.5s; }
.article-section:nth-child(7) { animation-delay: 0.6s; }
.article-section:nth-child(8) { animation-delay: 0.7s; }