:root {
  --primary: #1E3A8A;
  --secondary: #CED4DA;
  --accent: #FFC107;
  --highlight: #28A745;
  --text: #343A40;
  --light: #F8F9FA;
  --dark: #121212;
  --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

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

body {
  font-family: 'Roboto', sans-serif;
  background: linear-gradient(135deg, var(--light) 0%, #e6e9f0 100%);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
}

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

.header {
  background: linear-gradient(90deg, var(--primary) 0%, #2C5282 100%);
  color: white;
  padding: 2rem 0;
  text-align: center;
  margin-bottom: 3rem;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
  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 h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  position: relative;
  z-index: 1;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

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

.notice {
  background-color: var(--accent);
  color: white;
  padding: 1rem;
  text-align: center;
  font-weight: bold;
  margin-bottom: 2rem;
  border-radius: 4px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.article-container {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
  margin-bottom: 3rem;
}

article {
  background: white;
  border-radius: 8px;
  padding: 2rem;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
  position: relative;
  overflow: hidden;
}

article::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 100px;
  height: 100px;
  background: radial-gradient(circle, rgba(30, 58, 138, 0.1) 0%, rgba(30, 58, 138, 0) 70%);
  z-index: 0;
}

article h2 {
  color: var(--primary);
  margin-bottom: 1.5rem;
  font-size: 1.8rem;
  position: relative;
  z-index: 1;
}

article h3 {
  color: var(--primary);
  margin: 2rem 0 1rem;
  font-size: 1.4rem;
  position: relative;
  padding-left: 1rem;
  border-left: 4px solid var(--accent);
}

article p {
  margin-bottom: 1.5rem;
  position: relative;
  z-index: 1;
}

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

.image-grid img {
  width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  transition: var(--transition);
}

.image-grid img:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
}

pre {
  background: #f5f7fa;
  border-radius: 8px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  overflow: auto;
  border-left: 4px solid var(--accent);
  font-family: 'Courier New', monospace;
  position: relative;
}

pre::before {
  content: "CSS";
  position: absolute;
  top: 0;
  right: 0;
  background: var(--accent);
  color: white;
  padding: 0.2rem 0.8rem;
  font-size: 0.8rem;
  border-radius: 0 0 0 4px;
}

code {
  font-family: 'Courier New', monospace;
  background: rgba(255, 193, 7, 0.1);
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
  color: #d63384;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
}

.nav-link {
  background: white;
  padding: 0.8rem 1.5rem;
  border-radius: 30px;
  color: var(--primary);
  text-decoration: none;
  font-weight: 500;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  transition: var(--transition);
  border: 1px solid rgba(30, 58, 138, 0.1);
}

.nav-link:hover {
  background: var(--primary);
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
}

.footer {
  background: linear-gradient(90deg, var(--primary) 0%, #2C5282 100%);
  color: white;
  padding: 2rem 0;
  text-align: center;
  margin-top: 3rem;
}

.footer p {
  margin-bottom: 0;
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2rem;
  }
  
  .header p {
    font-size: 1rem;
  }
  
  article {
    padding: 1.5rem;
  }
  
  article h2 {
    font-size: 1.5rem;
  }
  
  article h3 {
    font-size: 1.2rem;
  }
  
  .image-grid {
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  }
}

@media (max-width: 480px) {
  .header h1 {
    font-size: 1.8rem;
  }
  
  .nav-links {
    justify-content: center;
  }
  
  .nav-link {
    padding: 0.6rem 1.2rem;
    font-size: 0.9rem;
  }
  
  pre {
    padding: 1rem;
    font-size: 0.9rem;
  }
}

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

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

.highlight-box {
  background: linear-gradient(135deg, rgba(30, 58, 138, 0.05) 0%, rgba(255, 193, 7, 0.05) 100%);
  border-left: 4px solid var(--accent);
  padding: 1.5rem;
  margin: 2rem 0;
  border-radius: 0 8px 8px 0;
}

.highlight-box h4 {
  color: var(--primary);
  margin-bottom: 1rem;
}

.toggle-content {
  margin: 1.5rem 0;
}

.toggle-btn {
  background: var(--primary);
  color: white;
  border: none;
  padding: 0.8rem 1.5rem;
  border-radius: 4px;
  cursor: pointer;
  font-weight: 500;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.toggle-btn:hover {
  background: #2C5282;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.toggle-btn::after {
  content: "+";
  font-size: 1.2rem;
}

.toggle-btn.active::after {
  content: "-";
}

.toggle-panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
  background: white;
  border-radius: 0 0 8px 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
}

.toggle-panel.active {
  max-height: 1000px;
  padding: 1.5rem;
  border-top: 1px solid rgba(0, 0, 0, 0.1);
}