:root {
  --primary-color: #1E90FF;
  --accent-color: #FF6347;
  --background-color: #F5F5F5;
  --dark-bg: #2c2c2c;
  --text-dark: #333;
  --text-light: #f5f5f5;
  --card-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

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

body {
  font-family: 'Roboto', sans-serif;
  background: linear-gradient(135deg, #f5f7fa 0%, #e4e8eb 100%);
  color: var(--text-dark);
  line-height: 1.6;
  overflow-x: hidden;
}

.header-notice {
  background: linear-gradient(90deg, var(--primary-color) 0%, #4b6cb7 100%);
  color: white;
  text-align: center;
  padding: 12px;
  font-size: 14px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  position: relative;
  z-index: 100;
}

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

.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 400px;
  background: url('https://images.gptkong.com/demo/sample1.png') center/cover no-repeat;
  position: relative;
  border-radius: 0 0 20px 20px;
  margin-bottom: 60px;
  box-shadow: var(--card-shadow);
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(30, 144, 255, 0.7);
  border-radius: 0 0 20px 20px;
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  color: white;
  padding: 40px;
  max-width: 800px;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 20px;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

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

.content-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  margin-bottom: 60px;
}

.article-card {
  background: white;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.article-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 15px 35px rgba(0, 0, 0, 0.15);
}

.article-header {
  padding: 30px;
  background: linear-gradient(90deg, var(--primary-color) 0%, #4b6cb7 100%);
  color: white;
}

.article-header h2 {
  font-size: 1.8rem;
  margin-bottom: 10px;
}

.article-body {
  padding: 30px;
}

.article-body h3 {
  color: var(--primary-color);
  margin: 25px 0 15px;
  font-size: 1.4rem;
  position: relative;
  padding-left: 15px;
}

.article-body h3::before {
  content: '';
  position: absolute;
  left: 0;
  top: 5px;
  height: 70%;
  width: 4px;
  background: var(--accent-color);
  border-radius: 2px;
}

.article-body p {
  margin-bottom: 20px;
  font-size: 1.1rem;
}

.code-block {
  background: #282c34;
  color: #abb2bf;
  padding: 20px;
  border-radius: 8px;
  margin: 20px 0;
  overflow-x: auto;
  font-family: 'Courier New', monospace;
  font-size: 0.95rem;
  line-height: 1.5;
  position: relative;
}

.code-block::before {
  content: 'CSS';
  position: absolute;
  top: 0;
  right: 0;
  background: var(--accent-color);
  color: white;
  padding: 3px 10px;
  font-size: 0.8rem;
  border-radius: 0 0 0 8px;
}

.image-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin: 30px 0;
}

.gallery-image {
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease;
  height: 300px;
}

.gallery-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.gallery-image:hover {
  transform: translateY(-5px);
}

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

.toggle-section {
  margin: 30px 0;
}

.toggle-header {
  background: linear-gradient(90deg, var(--primary-color) 0%, #4b6cb7 100%);
  color: white;
  padding: 15px 20px;
  border-radius: 8px 8px 0 0;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.toggle-header h4 {
  font-size: 1.2rem;
}

.toggle-content {
  background: white;
  padding: 20px;
  border-radius: 0 0 8px 8px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
  display: none;
}

.toggle-content.active {
  display: block;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.nav-links {
  display: flex;
  justify-content: center;
  margin: 40px 0;
  flex-wrap: wrap;
  gap: 15px;
}

.nav-link {
  background: var(--primary-color);
  color: white;
  padding: 12px 25px;
  border-radius: 30px;
  text-decoration: none;
  transition: all 0.3s ease;
  font-weight: 500;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.nav-link:hover {
  background: var(--accent-color);
  transform: translateY(-3px);
  box-shadow: 0 7px 14px rgba(0, 0, 0, 0.15);
}

.footer {
  background: linear-gradient(90deg, var(--primary-color) 0%, #4b6cb7 100%);
  color: white;
  text-align: center;
  padding: 30px;
  margin-top: 60px;
  border-radius: 20px 20px 0 0;
}

@media (max-width: 768px) {
  .hero {
    min-height: 300px;
    margin-bottom: 40px;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: 1rem;
  }
  
  .article-header h2 {
    font-size: 1.5rem;
  }
  
  .article-body h3 {
    font-size: 1.2rem;
  }
  
  .image-gallery {
    grid-template-columns: 1fr;
  }
}

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

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

.pulse {
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); }
}