:root {
  --primary: linear-gradient(135deg, #0D47A1, #8E24AA);
  --secondary: #37474F;
  --accent: #FF9800;
  --text: #212121;
  --light: #FFFFFF;
  --shadow: 0 4px 20px rgba(0,0,0,0.1);
}

body {
  font-family: 'Roboto', sans-serif;
  color: var(--text);
  background: #F5F5F5;
  margin: 0;
  line-height: 1.6;
}

header {
  background: var(--primary);
  color: var(--light);
  padding: 2rem;
  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;
  opacity: 0.1;
}

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

h2, h3 {
  color: #0D47A1;
  position: relative;
  padding-left: 1rem;
}

h2::before, h3::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 4px;
  height: 80%;
  background: var(--primary);
  border-radius: 2px;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
  gap: 2rem;
  margin: 3rem 0;
}

.card {
  background: var(--light);
  border-radius: 12px;
  box-shadow: var(--shadow);
  padding: 2rem;
  transition: all 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

.code-block {
  background: #263238;
  color: #ECEFF1;
  padding: 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-family: 'Consolas', monospace;
  position: relative;
}

.code-block::before {
  content: "CSS";
  position: absolute;
  top: 0;
  right: 0;
  background: #8E24AA;
  color: white;
  padding: 0.3rem 0.8rem;
  border-radius: 0 0 0 8px;
  font-size: 0.8rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 2rem 0;
  box-shadow: var(--shadow);
}

th, td {
  padding: 1rem;
  text-align: left;
  border-bottom: 1px solid #E0E0E0;
}

th {
  background: #0D47A1;
  color: white;
}

tr:nth-child(even) {
  background: #F5F5F5;
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.image-card {
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: all 0.3s ease;
}

.image-card:hover {
  transform: scale(1.03);
}

.image-card img {
  width: 100%;
  height: auto;
  display: block;
}

.notice {
  background: rgba(255,152,0,0.1);
  border-left: 4px solid var(--accent);
  padding: 1rem;
  margin: 2rem 0;
  font-style: italic;
}

@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
  }
  
  h1 {
    font-size: 2rem;
  }
}

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

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

.nav-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin: 2rem 0;
}

.nav-link {
  padding: 0.8rem 1.5rem;
  background: var(--primary);
  color: white;
  border-radius: 30px;
  text-decoration: none;
  transition: all 0.3s ease;
  font-weight: 500;
}

.nav-link:hover {
  transform: translateY(-3px);
  box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}