:root {
  --primary-color: #2B354F;
  --secondary-color: #E0E3E6;
  --accent-color: #FF8C00;
  --background-color: #F7F9FB;
  --text-color: #333;
  --light-color: #fff;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  --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', 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background: var(--background-color);
  overflow-x: hidden;
}

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

.header {
  background: linear-gradient(135deg, var(--primary-color), #1a2238);
  color: var(--light-color);
  padding: 2rem 0;
  text-align: center;
  position: relative;
  overflow: hidden;
  margin-bottom: 3rem;
}

.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: 0.2;
}

.header h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  position: relative;
  z-index: 1;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.header p {
  font-size: 1.2rem;
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.notice {
  background: var(--accent-color);
  color: var(--light-color);
  padding: 1rem;
  text-align: center;
  font-weight: bold;
  margin-bottom: 2rem;
  border-radius: 4px;
  box-shadow: var(--shadow);
}

.nav-tabs {
  display: flex;
  justify-content: center;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  gap: 10px;
}

.nav-tabs a {
  color: var(--primary-color);
  text-decoration: none;
  padding: 0.8rem 1.5rem;
  border-radius: 30px;
  background: var(--secondary-color);
  transition: var(--transition);
  font-weight: 500;
  margin: 0 5px;
  border: 2px solid transparent;
}

.nav-tabs a:hover {
  background: var(--primary-color);
  color: var(--light-color);
  transform: translateY(-3px);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

article {
  background: var(--light-color);
  padding: 2rem;
  border-radius: 8px;
  box-shadow: var(--shadow);
  margin-bottom: 3rem;
}

article h2 {
  color: var(--primary-color);
  margin-bottom: 1.5rem;
  font-size: 1.8rem;
  position: relative;
  padding-bottom: 10px;
}

article h2::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100px;
  height: 3px;
  background: linear-gradient(to right, var(--accent-color), transparent);
}

article h3 {
  color: var(--primary-color);
  margin: 2rem 0 1rem;
  font-size: 1.5rem;
}

article p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
  line-height: 1.8;
}

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

.card {
  background: var(--light-color);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: var(--transition);
  perspective: 1000px;
}

.card:hover {
  transform: translateY(-10px);
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.2);
}

.card-img {
  height: 200px;
  overflow: hidden;
}

.card-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.card:hover .card-img img {
  transform: scale(1.1);
}

.card-content {
  padding: 1.5rem;
}

.card-content h4 {
  color: var(--primary-color);
  margin-bottom: 1rem;
}

pre {
  background: #282c34;
  color: #abb2bf;
  padding: 1.5rem;
  border-radius: 6px;
  overflow-x: auto;
  margin: 2rem 0;
  font-size: 0.9rem;
  line-height: 1.5;
  position: relative;
}

pre::before {
  content: "CSS";
  position: absolute;
  top: 0;
  left: 0;
  background: var(--accent-color);
  color: var(--light-color);
  padding: 0.2rem 0.8rem;
  font-size: 0.8rem;
  border-radius: 0 0 4px 0;
}

.chart-container {
  display: flex;
  justify-content: center;
  align-items: flex-end;
  height: 300px;
  margin: 2rem 0;
  gap: 20px;
}

.chart-bar {
  width: 50px;
  background: linear-gradient(to top, var(--accent-color), #ff6b00);
  border-radius: 4px 4px 0 0;
  transition: height 0.5s ease;
  position: relative;
}

.chart-bar::after {
  content: attr(data-value);
  position: absolute;
  top: -30px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary-color);
  color: var(--light-color);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  font-size: 0.8rem;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.chart-bar:hover::after {
  opacity: 1;
}

.footer {
  background: var(--primary-color);
  color: var(--light-color);
  padding: 2rem 0;
  text-align: center;
  margin-top: 3rem;
}

.footer p {
  margin-bottom: 0;
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2rem;
  }
  
  .nav-tabs {
    flex-direction: column;
    align-items: center;
  }
  
  .nav-tabs a {
    width: 100%;
    margin: 5px 0;
  }
  
  article {
    padding: 1.5rem;
  }
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-10px); }
  100% { transform: translateY(0px); }
}

.floating {
  animation: float 3s ease-in-out infinite;
}

.highlight {
  background: linear-gradient(90deg, rgba(255,140,0,0.2), transparent);
  padding: 0.2rem 0.5rem;
  border-left: 3px solid var(--accent-color);
}