:root {
  --primary: #1E90FF;
  --secondary: #FFA500;
  --bg-gradient: linear-gradient(135deg, #f0f0f0 0%, #1E90FF 100%);
  --text-dark: #333;
  --text-light: #fff;
  --card-bg: rgba(255,255,255,0.9);
  --shadow: 0 10px 30px rgba(0,0,0,0.1);
}

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

body {
  background: var(--bg-gradient);
  color: var(--text-dark);
  line-height: 1.6;
  padding-top: 80px;
}

.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: rgba(255,255,255,0.95);
  box-shadow: 0 2px 20px rgba(0,0,0,0.1);
  z-index: 1000;
  padding: 15px 5%;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

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

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

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

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

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

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

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

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

.banner::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(30, 144, 255, 0.3);
}

.banner-content {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 0 20px;
  color: var(--text-light);
}

.banner h1 {
  font-size: 48px;
  margin-bottom: 20px;
  text-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

.banner p {
  font-size: 20px;
  max-width: 700px;
  margin: 0 auto 30px;
}

.notice {
  background: var(--secondary);
  color: white;
  padding: 15px;
  text-align: center;
  margin-bottom: 40px;
  border-radius: 8px;
  font-weight: 500;
  box-shadow: 0 4px 15px rgba(255,165,0,0.3);
}

article {
  background: var(--card-bg);
  border-radius: 20px;
  padding: 40px;
  margin-bottom: 60px;
  box-shadow: var(--shadow);
}

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

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

article h3 {
  color: var(--primary);
  font-size: 24px;
  margin: 25px 0 15px;
}

article h4 {
  color: var(--text-dark);
  font-size: 20px;
  margin: 20px 0 10px;
}

article p {
  margin-bottom: 20px;
  font-size: 17px;
}

article strong {
  color: var(--primary);
}

article em {
  color: var(--secondary);
  font-style: normal;
  font-weight: 500;
}

.color-box {
  display: inline-block;
  width: 20px;
  height: 20px;
  border-radius: 4px;
  vertical-align: middle;
  margin: 0 5px;
  box-shadow: 0 0 5px rgba(0,0,0,0.2);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 30px;
  margin: 40px 0;
}

.card {
  grid-column: span 4;
  background: white;
  border-radius: 15px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-10px);
  box-shadow: 0 15px 40px rgba(0,0,0,0.15);
}

.card-img {
  height: 200px;
  background-size: cover;
  background-position: center;
}

.card-content {
  padding: 25px;
}

.card h3 {
  color: var(--primary);
  margin-bottom: 15px;
  font-size: 20px;
}

.card p {
  color: var(--text-dark);
  font-size: 15px;
}

pre {
  background: #2d2d2d;
  color: #f8f8f2;
  padding: 20px;
  border-radius: 8px;
  overflow-x: auto;
  margin: 25px 0;
  font-size: 15px;
  line-height: 1.5;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

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

.button {
  display: inline-block;
  background: var(--secondary);
  color: white;
  padding: 12px 25px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
  margin: 10px 0;
}

.button:hover {
  background: #e69500;
  transform: translateY(-2px);
}

.footer {
  background: rgba(0,0,0,0.8);
  color: white;
  padding: 40px 0;
  text-align: center;
}

.footer p {
  margin-bottom: 10px;
}

.footer a {
  color: var(--secondary);
  text-decoration: none;
  transition: color 0.3s ease;
}

.footer a:hover {
  color: #ffc04d;
}

@media (max-width: 1024px) {
  .card {
    grid-column: span 6;
  }
}

@media (max-width: 768px) {
  .nav {
    gap: 15px;
  }
  
  .banner h1 {
    font-size: 36px;
  }
  
  .banner p {
    font-size: 18px;
  }
  
  article {
    padding: 30px;
  }
}

@media (max-width: 600px) {
  .header {
    flex-direction: column;
    padding: 15px;
  }
  
  .logo {
    margin-bottom: 15px;
  }
  
  .nav {
    flex-wrap: wrap;
    justify-content: center;
  }
  
  .card {
    grid-column: span 12;
  }
  
  article h2 {
    font-size: 28px;
  }
  
  article h3 {
    font-size: 22px;
  }
}

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

.fade-in {
  animation: fadeIn 0.8s ease forwards;
}

.delay-1 {
  animation-delay: 0.2s;
}

.delay-2 {
  animation-delay: 0.4s;
}

.delay-3 {
  animation-delay: 0.6s;
}

.visible {
  opacity: 1 !important;
  transform: translateY(0) !important;
}