:root {
  --primary-blue: #1E90FF;
  --secondary-white: #FFFFFF;
  --accent-purple: linear-gradient(135deg, #6A5ACD, #9370DB);
  --accent-orange: linear-gradient(135deg, #FFA07A, #FF7F50);
  --dark-blue: #0A2463;
  --light-gray: #F5F7FA;
  --shadow-color: rgba(0, 0, 0, 0.1);
}

body {
  font-family: 'Roboto', sans-serif;
  background: var(--light-gray);
  color: #333;
  line-height: 1.6;
  margin: 0;
  padding: 0;
}

header {
  background: linear-gradient(135deg, var(--primary-blue), var(--dark-blue));
  color: white;
  padding: 2rem;
  text-align: center;
  margin-bottom: 3rem;
  box-shadow: 0 4px 12px var(--shadow-color);
}

h1 {
  font-size: 2.5rem;
  margin: 0;
  padding: 1rem 0;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

h2 {
  font-size: 1.8rem;
  color: var(--primary-blue);
  margin: 2rem 0 1rem;
  position: relative;
  padding-bottom: 0.5rem;
}

h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100px;
  height: 3px;
  background: var(--accent-purple);
}

h3 {
  font-size: 1.5rem;
  color: var(--dark-blue);
  margin: 1.5rem 0 1rem;
}

p {
  margin: 1rem 0;
  font-size: 1.1rem;
}

.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: white;
  border-radius: 12px;
  padding: 2rem;
  box-shadow: 0 8px 16px var(--shadow-color);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 24px rgba(0,0,0,0.15);
}

.code-block {
  background: #282C34;
  color: #ABB2BF;
  padding: 1.5rem;
  border-radius: 8px;
  margin: 1.5rem 0;
  overflow-x: auto;
  font-family: 'Fira Code', monospace;
  box-shadow: inset 0 0 10px rgba(0,0,0,0.3);
}

.code-block code {
  display: block;
  white-space: pre;
}

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

.img-container img {
  width: 150px;
  height: 150px;
  object-fit: cover;
  border-radius: 8px;
  box-shadow: 0 4px 8px var(--shadow-color);
  transition: transform 0.3s ease;
}

.img-container img:hover {
  transform: scale(1.05);
}

.nav-tabs {
  display: flex;
  gap: 1rem;
  margin: 2rem 0;
  padding: 0;
  list-style: none;
}

.nav-tabs li a {
  text-decoration: none;
  color: var(--primary-blue);
  padding: 0.5rem 1rem;
  border-radius: 4px;
  transition: background 0.3s ease;
}

.nav-tabs li a:hover {
  background: rgba(30, 144, 255, 0.1);
}

.notice {
  background: rgba(30, 144, 255, 0.1);
  border-left: 4px solid var(--primary-blue);
  padding: 1rem;
  margin: 2rem 0;
  border-radius: 0 4px 4px 0;
}

@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
}

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

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