:root {
  --primary-color: #001f3f;
  --secondary-color: #FFFFFF;
  --accent-color: #FFA500;
  --hover-color: #FF4500;
  --gradient-blue: linear-gradient(135deg, #001f3f 0%, #003366 100%);
  --gradient-orange: linear-gradient(45deg, #FFA500 0%, #FF4500 100%);
  --shadow-lg: 0 10px 25px rgba(0, 31, 63, 0.15);
  --shadow-sm: 0 5px 15px rgba(0, 31, 63, 0.1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Helvetica Neue', Arial, sans-serif;
}

body {
  background-color: var(--secondary-color);
  color: var(--primary-color);
  line-height: 1.6;
  overflow-x: hidden;
}

.header-notice {
  background: var(--gradient-blue);
  color: white;
  text-align: center;
  padding: 12px;
  font-size: 14px;
  position: relative;
  z-index: 1001;
}

.navbar {
  position: sticky;
  top: 0;
  width: 100%;
  background: var(--gradient-blue);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 5%;
  z-index: 1000;
  box-shadow: var(--shadow-lg);
}

.navbar .logo {
  font-size: 24px;
  font-weight: 700;
  color: var(--secondary-color);
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: 30px;
}

.nav-links a {
  color: var(--secondary-color);
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s ease;
  position: relative;
}

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

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-color);
  transition: width 0.3s ease;
}

.nav-links a:hover::after {
  width: 100%;
}

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

.hero {
  height: 600px;
  display: flex;
  align-items: center;
  background: var(--gradient-blue);
  color: white;
  position: relative;
  overflow: hidden;
}

.hero::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: 0.2;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 600px;
}

.hero h1 {
  font-size: 48px;
  margin-bottom: 20px;
  line-height: 1.2;
}

.hero p {
  font-size: 18px;
  margin-bottom: 30px;
}

.btn {
  display: inline-block;
  padding: 15px 30px;
  background: var(--gradient-orange);
  color: white;
  border: none;
  border-radius: 50px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: var(--shadow-sm);
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 20px rgba(255, 165, 0, 0.3);
}

article {
  padding: 80px 0;
}

article h2 {
  font-size: 32px;
  margin-bottom: 30px;
  color: var(--primary-color);
  position: relative;
  padding-bottom: 15px;
}

article h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 80px;
  height: 4px;
  background: var(--gradient-orange);
}

article h3 {
  font-size: 24px;
  margin: 40px 0 20px;
  color: var(--primary-color);
}

article p {
  font-size: 17px;
  margin-bottom: 25px;
  line-height: 1.7;
}

.code-container {
  background: #f5f7fa;
  border-radius: 8px;
  padding: 25px;
  margin: 30px 0;
  overflow: auto;
  box-shadow: var(--shadow-sm);
  border-left: 4px solid var(--accent-color);
}

pre {
  margin: 0;
  font-family: 'Courier New', monospace;
  font-size: 15px;
  line-height: 1.5;
  color: #333;
}

.split-section {
  display: flex;
  gap: 40px;
  margin: 60px 0;
  align-items: center;
}

.split-section.reverse {
  flex-direction: row-reverse;
}

.split-section .text-content {
  flex: 1;
}

.split-section .image-content {
  flex: 1;
  position: relative;
}

.split-section img {
  width: 100%;
  border-radius: 8px;
  box-shadow: var(--shadow-lg);
  transition: transform 0.3s ease;
}

.split-section img:hover {
  transform: scale(1.02);
}

.image-decor {
  position: absolute;
  width: 100px;
  height: 100px;
  background: var(--gradient-orange);
  border-radius: 50%;
  z-index: -1;
}

.image-decor-1 {
  top: -20px;
  left: -20px;
}

.image-decor-2 {
  bottom: -20px;
  right: -20px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin: 60px 0;
}

.feature-card {
  background: white;
  border-radius: 10px;
  padding: 30px;
  box-shadow: var(--shadow-sm);
  transition: all 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-lg);
}

.feature-card img {
  width: 80px;
  height: 80px;
  margin-bottom: 20px;
  border-radius: 50%;
  object-fit: cover;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.feature-card h4 {
  font-size: 20px;
  margin-bottom: 15px;
  color: var(--primary-color);
}

.footer {
  background: var(--gradient-blue);
  color: white;
  padding: 60px 0 30px;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 40px;
  margin-bottom: 40px;
}

.footer-column h4 {
  font-size: 18px;
  margin-bottom: 20px;
  position: relative;
  padding-bottom: 10px;
}

.footer-column h4::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 50px;
  height: 2px;
  background: var(--accent-color);
}

.footer-column ul {
  list-style: none;
}

.footer-column ul li {
  margin-bottom: 10px;
}

.footer-column a {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: none;
  transition: color 0.3s ease;
}

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

.copyright {
  text-align: center;
  padding-top: 30px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  font-size: 14px;
}

@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    padding: 15px;
  }
  
  .nav-links {
    margin-top: 15px;
    gap: 15px;
  }
  
  .hero {
    height: auto;
    padding: 80px 0;
    text-align: center;
  }
  
  .hero h1 {
    font-size: 36px;
  }
  
  .split-section {
    flex-direction: column;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
}

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

.module {
  opacity: 0;
  animation: fadeIn 0.6s ease-out forwards;
}

.module:nth-child(1) { animation-delay: 0.1s; }
.module:nth-child(2) { animation-delay: 0.2s; }
.module:nth-child(3) { animation-delay: 0.3s; }
.module:nth-child(4) { animation-delay: 0.4s; }
.module:nth-child(5) { animation-delay: 0.5s; }