:root {
  --primary-color: #03A9F4;
  --background-color: #F5F5F5;
  --accent-color-orange: #FFC107;
  --accent-color-green: #8BC34A;
  --dark-color: #263238;
  --light-color: #ECEFF1;
}

@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500;700&display=swap');

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

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

.header {
  background: linear-gradient(90deg, var(--primary-color) 0%, #0288D1 100%);
  color: white;
  padding: 2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.header::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('https://images.gptkong.com/demo/sample8.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;
}

.note {
  background-color: rgba(255,255,255,0.9);
  color: var(--dark-color);
  padding: 1rem;
  border-radius: 8px;
  margin: 2rem auto;
  max-width: 800px;
  text-align: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  font-weight: 500;
}

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

.section {
  background-color: white;
  border-radius: 12px;
  padding: 2rem;
  margin-bottom: 3rem;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  position: relative;
  overflow: hidden;
}

.section:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.12);
}

.section::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color-green));
}

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

.section h2::after {
  content: "";
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color-orange));
}

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

.code-container {
  background-color: #f8f9fa;
  border-radius: 8px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  overflow: auto;
  border-left: 4px solid var(--primary-color);
}

pre {
  margin: 0;
  font-family: 'Roboto Mono', monospace;
  font-size: 0.95rem;
  line-height: 1.5;
  color: #333;
}

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

.gallery-item {
  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;
}

.gallery-item:hover {
  transform: translateY(-8px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.15);
}

.gallery-item img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform 0.5s ease;
}

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

.button {
  display: inline-block;
  padding: 0.8rem 1.5rem;
  background: linear-gradient(45deg, var(--primary-color), #0288D1);
  color: white;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  margin: 0.5rem 0;
}

.button:hover {
  background: linear-gradient(45deg, #0288D1, var(--primary-color));
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  transform: translateY(-2px);
}

.footer {
  background: linear-gradient(90deg, var(--dark-color) 0%, #37474F 100%);
  color: white;
  padding: 3rem 2rem;
  text-align: center;
  margin-top: 3rem;
}

.footer p {
  margin-bottom: 1rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin: 1.5rem 0;
}

.footer-links a {
  color: white;
  text-decoration: none;
  transition: color 0.3s ease;
}

.footer-links a:hover {
  color: var(--accent-color-orange);
}

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

@media (max-width: 480px) {
  .header h1 {
    font-size: 1.8rem;
  }
  
  .section h2 {
    font-size: 1.5rem;
  }
  
  .footer-links {
    flex-direction: column;
    gap: 1rem;
  }
}

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

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

.section:nth-child(1) { animation-delay: 0.1s; }
.section:nth-child(2) { animation-delay: 0.2s; }
.section:nth-child(3) { animation-delay: 0.3s; }
.section:nth-child(4) { animation-delay: 0.4s; }
.section:nth-child(5) { animation-delay: 0.5s; }
.section:nth-child(6) { animation-delay: 0.6s; }
.section:nth-child(7) { animation-delay: 0.7s; }
.section:nth-child(8) { animation-delay: 0.8s; }

/* Navigation */
.nav-tabs {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  margin: 2rem 0;
  gap: 1rem;
}

.nav-tab {
  padding: 0.8rem 1.5rem;
  background: rgba(3, 169, 244, 0.1);
  color: var(--primary-color);
  border-radius: 6px;
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s ease;
}

.nav-tab:hover {
  background: rgba(3, 169, 244, 0.2);
  transform: translateY(-2px);
}

.nav-tab.active {
  background: var(--primary-color);
  color: white;
}