:root {
  --primary-color: #0A2640;
  --accent-color: #38B000;
  --background-color: #FFFFFF;
  --light-gray: #F5F5F5;
  --dark-gray: #333333;
  --gradient-blue: linear-gradient(135deg, #0A2640 0%, #144E8C 100%);
  --gradient-green: linear-gradient(135deg, #38B000 0%, #6FD91A 100%);
  --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 20px 25px rgba(0, 0, 0, 0.1);
}

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

body {
  font-family: 'Roboto', sans-serif;
  color: var(--dark-gray);
  background-color: var(--background-color);
  line-height: 1.6;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-family: 'Poppins', sans-serif;
  color: var(--primary-color);
  margin-bottom: 1.5rem;
  font-weight: 600;
}

h2 {
  font-size: 2.2rem;
  position: relative;
  padding-bottom: 1rem;
  margin-top: 3rem;
}

h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 80px;
  height: 4px;
  background: var(--gradient-green);
  border-radius: 2px;
}

h3 {
  font-size: 1.8rem;
  margin-top: 2.5rem;
}

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

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

.header {
  background: var(--gradient-blue);
  color: white;
  padding: 100px 0;
  text-align: center;
  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-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.header h1 {
  font-size: 3rem;
  margin-bottom: 1.5rem;
  color: white;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.header p {
  font-size: 1.3rem;
  color: rgba(255,255,255,0.9);
  margin-bottom: 2rem;
}

.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: rgba(10, 38, 64, 0.95);
  box-shadow: var(--shadow-sm);
  z-index: 1000;
  backdrop-filter: blur(10px);
  padding: 15px 0;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.nav-logo {
  font-family: 'Poppins', sans-serif;
  font-weight: 700;
  font-size: 1.5rem;
  color: white;
  text-decoration: none;
}

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

.nav-links a {
  color: white;
  text-decoration: none;
  font-family: 'Poppins', sans-serif;
  font-weight: 500;
  position: relative;
  padding: 5px 0;
  transition: color 0.3s ease;
}

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

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

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

.main-content {
  padding-top: 100px;
  padding-bottom: 100px;
}

.section {
  padding: 80px 0;
}

.section:nth-child(even) {
  background-color: var(--light-gray);
}

.section-content {
  max-width: 1000px;
  margin: 0 auto;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin: 40px 0;
}

.card {
  background: white;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

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

.card-img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.card-content {
  padding: 25px;
}

.card h3 {
  margin-bottom: 15px;
  font-size: 1.5rem;
}

.notice {
  background: rgba(56, 176, 0, 0.1);
  border-left: 4px solid var(--accent-color);
  padding: 20px;
  margin: 40px 0;
  border-radius: 0 5px 5px 0;
}

.notice p {
  margin: 0;
  color: var(--primary-color);
  font-weight: 500;
}

pre {
  background: #f8f8f8;
  border-radius: 8px;
  padding: 20px;
  margin: 30px 0;
  overflow: auto;
  box-shadow: var(--shadow-sm);
  border-left: 4px solid var(--accent-color);
}

code {
  font-family: 'Courier New', monospace;
  color: #333;
}

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

.footer p {
  margin-bottom: 0;
  opacity: 0.8;
}

.img-container {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  margin: 40px 0;
  justify-content: center;
}

.img-wrapper {
  width: 320px;
  height: 320px;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.img-wrapper:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-md);
}

.img-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.button {
  display: inline-block;
  background: var(--gradient-green);
  color: white;
  padding: 12px 25px;
  border-radius: 5px;
  text-decoration: none;
  font-weight: 500;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  box-shadow: var(--shadow-sm);
}

.button:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2.2rem;
  }
  
  .header p {
    font-size: 1.1rem;
  }
  
  h2 {
    font-size: 1.8rem;
  }
  
  h3 {
    font-size: 1.5rem;
  }
  
  .nav-links {
    gap: 15px;
  }
  
  .grid {
    grid-template-columns: 1fr;
  }
}