:root {
    --primary-dark: #1E3A8A;
    --primary-light: #3B82F6;
    --accent: #F97316;
    --bg-light: linear-gradient(135deg, #ffffff, #f0f0f0);
    --bg-dark: linear-gradient(135deg, #2c3e50, #34495e);
    --text-dark: #333;
    --text-light: #ecf0f1;
    --shadow: 0 4px 20px rgba(0,0,0,0.1);
    --radius: 12px;
    --transition: all 0.3s ease;
  }

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

  body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background: var(--bg-light);
    padding: 20px;
    max-width: 1200px;
    margin: 0 auto;
  }

  .header {
    text-align: center;
    margin: 40px 0;
    position: relative;
  }

  .header::before {
    content: "";
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-light), var(--accent));
    border-radius: 3px;
  }

  h1, h2, h3 {
    color: var(--primary-dark);
    margin: 30px 0 15px;
    font-weight: 700;
  }

  h1 { font-size: 2.5rem; }
  h2 { font-size: 2rem; }
  h3 { font-size: 1.5rem; }

  p {
    margin-bottom: 20px;
    font-size: 1.1rem;
  }

  .notice {
    background: rgba(62, 128, 255, 0.1);
    border-left: 4px solid var(--primary-light);
    padding: 15px;
    margin: 30px 0;
    border-radius: 0 var(--radius) var(--radius) 0;
    font-size: 0.9rem;
  }

  .card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(500px, 1fr));
    gap: 30px;
    margin: 40px 0;
  }

  .card {
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: var(--transition);
    position: relative;
    perspective: 1000px;
  }

  .card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
  }

  .card-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-bottom: 1px solid rgba(0,0,0,0.1);
  }

  .card-content {
    padding: 25px;
  }

  .code-block {
    background: #282c34;
    color: #abb2bf;
    padding: 20px;
    border-radius: var(--radius);
    margin: 25px 0;
    overflow-x: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
  }

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

  .tag {
    display: inline-block;
    background: rgba(62, 128, 255, 0.1);
    color: var(--primary-light);
    padding: 3px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
    margin-right: 5px;
  }

  .flip-container {
    perspective: 1000px;
    margin: 30px 0;
  }

  .flipper {
    position: relative;
    width: 100%;
    height: 300px;
    transition: transform 0.8s;
    transform-style: preserve-3d;
  }

  .flip-container:hover .flipper {
    transform: rotateY(180deg);
  }

  .front, .back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
  }

  .back {
    transform: rotateY(180deg);
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .nav-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 15px;
    margin: 40px 0;
  }

  .nav-link {
    padding: 10px 20px;
    background: var(--primary-light);
    color: white;
    border-radius: 50px;
    text-decoration: none;
    transition: var(--transition);
    font-weight: 500;
  }

  .nav-link:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
  }

  .color-swatch {
    display: inline-block;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    margin-right: 5px;
    vertical-align: middle;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
  }

  @media (max-width: 768px) {
    .card-grid {
      grid-template-columns: 1fr;
    }
    
    h1 { font-size: 2rem; }
    h2 { font-size: 1.7rem; }
    h3 { font-size: 1.3rem; }
  }

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

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