:root {
  --primary-color: #2E4053;
  --secondary-color: #F5F5F5;
  --accent-orange: #FFA726;
  --accent-green: #81C784;
  --text-color: #333;
  --light-text: #777;
  --shadow: 0 4px 20px rgba(0,0,0,0.08);
  --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

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

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

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

.header {
  background: linear-gradient(135deg, var(--primary-color), #3A5169);
  color: white;
  padding: 60px 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: 2.8rem;
  margin-bottom: 20px;
  font-weight: 500;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.header p {
  font-size: 1.2rem;
  opacity: 0.9;
  margin-bottom: 30px;
}

.notice {
  background-color: rgba(255,255,255,0.2);
  padding: 15px;
  border-radius: 8px;
  display: inline-block;
  margin-top: 20px;
  font-size: 0.9rem;
}

.main-content {
  padding: 60px 0;
}

.article-container {
  background: white;
  border-radius: 12px;
  box-shadow: var(--shadow);
  padding: 40px;
  margin-bottom: 40px;
}

.article-container h2 {
  color: var(--primary-color);
  font-size: 1.8rem;
  margin-bottom: 25px;
  padding-bottom: 15px;
  border-bottom: 2px solid var(--accent-orange);
}

.article-container h3 {
  color: var(--primary-color);
  font-size: 1.4rem;
  margin: 30px 0 15px;
}

.article-container p {
  margin-bottom: 20px;
  font-size: 1.1rem;
  line-height: 1.7;
}

.code-container {
  background: #f8f9fa;
  border-left: 4px solid var(--accent-green);
  padding: 20px;
  margin: 25px 0;
  border-radius: 0 8px 8px 0;
  overflow: auto;
}

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

table {
  width: 100%;
  border-collapse: collapse;
  margin: 25px 0;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

th, td {
  padding: 12px 15px;
  text-align: left;
  border-bottom: 1px solid #ddd;
}

th {
  background-color: var(--primary-color);
  color: white;
  font-weight: 500;
}

tr:nth-child(even) {
  background-color: #f9f9f9;
}

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
  margin: 40px 0;
}

.gallery-item {
  background: white;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.gallery-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

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

.gallery-caption {
  padding: 15px;
  text-align: center;
}

.nav-tabs {
  display: flex;
  border-bottom: 1px solid #ddd;
  margin-bottom: 30px;
}

.nav-tab {
  padding: 10px 20px;
  cursor: pointer;
  border-bottom: 3px solid transparent;
  transition: var(--transition);
}

.nav-tab.active {
  border-bottom-color: var(--accent-orange);
  color: var(--primary-color);
  font-weight: 500;
}

.nav-tab:hover:not(.active) {
  border-bottom-color: #ccc;
}

.footer {
  background-color: var(--primary-color);
  color: white;
  padding: 40px 0;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.footer-link {
  color: white;
  margin: 0 15px;
  text-decoration: none;
  transition: var(--transition);
}

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

.footer-text {
  opacity: 0.8;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2rem;
  }
  
  .header p {
    font-size: 1rem;
  }
  
  .article-container {
    padding: 25px;
  }
  
  .gallery {
    grid-template-columns: 1fr;
  }
}

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

.animated {
  animation: fadeIn 0.6s ease-out forwards;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }
.delay-3 { animation-delay: 0.6s; }

/* Decorative elements */
.decorative-line {
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent-orange), transparent);
  margin: 40px 0;
  opacity: 0.5;
}

.tech-dot {
  width: 8px;
  height: 8px;
  background-color: var(--accent-green);
  border-radius: 50%;
  display: inline-block;
  margin: 0 5px;
}