:root {
  --primary: #1E3A8A;
  --secondary: #3B82F6;
  --accent: #F97316;
  --light: #F3F4F6;
  --dark: #111827;
  --text: #374151;
  --white: #FFFFFF;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Roboto', 'Open Sans', sans-serif;
}

body {
  background-color: var(--light);
  color: var(--text);
  line-height: 1.6;
  font-size: 16px;
  overflow-x: hidden;
}

.header-banner {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--white);
  padding: 2rem;
  text-align: center;
  margin-bottom: 3rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.header-banner h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.notice {
  background: rgba(255,255,255,0.15);
  padding: 1rem;
  border-radius: 8px;
  display: inline-block;
  margin-top: 1rem;
  font-size: 0.9rem;
}

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

article {
  background: var(--white);
  border-radius: 12px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  padding: 3rem;
  margin-bottom: 3rem;
}

article h2 {
  color: var(--primary);
  font-size: 2rem;
  margin-bottom: 1.5rem;
  position: relative;
  padding-bottom: 0.5rem;
}

article h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 80px;
  height: 4px;
  background: linear-gradient(90deg, var(--accent), #FB923C);
  border-radius: 2px;
}

article h3 {
  color: var(--secondary);
  font-size: 1.5rem;
  margin: 2rem 0 1rem;
}

article p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
  line-height: 1.8;
}

.code-container {
  background: #1E1E1E;
  border-radius: 8px;
  padding: 1.5rem;
  margin: 2rem 0;
  overflow: hidden;
  position: relative;
}

.code-container::before {
  content: 'CSS';
  position: absolute;
  top: 0;
  right: 0;
  background: var(--accent);
  color: var(--white);
  padding: 0.25rem 0.75rem;
  font-size: 0.8rem;
  border-bottom-left-radius: 8px;
}

pre {
  color: #D4D4D4;
  font-family: 'Consolas', monospace;
  font-size: 0.9rem;
  line-height: 1.5;
  white-space: pre-wrap;
  word-wrap: break-word;
}

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

.image-card {
  background: var(--white);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 4px 12px 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 8px 24px rgba(0,0,0,0.15);
}

.image-card img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 12px 12px 0 0;
}

.image-caption {
  padding: 1rem;
  text-align: center;
  font-size: 0.9rem;
  color: var(--text);
}

.nav-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid #E5E7EB;
  padding-bottom: 1rem;
}

.nav-tabs a {
  color: var(--text);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  transition: all 0.3s ease;
  font-weight: 500;
}

.nav-tabs a:hover {
  background: rgba(59, 130, 246, 0.1);
  color: var(--secondary);
}

.nav-tabs a.active {
  background: var(--secondary);
  color: var(--white);
}

@media (max-width: 768px) {
  .container {
    padding: 0 1rem;
  }
  
  article {
    padding: 2rem 1rem;
  }
  
  .image-grid {
    grid-template-columns: 1fr;
  }
  
  .header-banner h1 {
    font-size: 2rem;
  }
}

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

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

.highlight {
  background: linear-gradient(120deg, rgba(251,146,60,0.3), rgba(251,146,60,0));
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
}