:root {
    --space-blue: #0A1128;
    --cyber-blue: #00DDEB;
    --neon-purple: #9B5DE5;
    --frost-white: #F5F7FA;
    --cyan-glow: #78E3FD;
    --gray-dark: #1E2A44;
  }
  
  @import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@400;700&family=Roboto:wght@300;400;700&display=swap');
  
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  body {
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(180deg, var(--space-blue) 0%, var(--gray-dark) 100%);
    color: var(--frost-white);
    line-height: 1.6;
  }
  
  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
  }
  

  .navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(10, 17, 40, 0.8);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 0;
  }
  
  .navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  
  .logo {
    font-family: 'Orbitron', sans-serif;
    font-size: 1.8rem;
    color: var(--cyber-blue);
    text-transform: uppercase;
    letter-spacing: 2px;
  }
  
  .nav-links {
    display: flex;
    align-items: center;
    gap: 2rem;
  }
  
  .nav-links a {
    color: var(--frost-white);
    text-decoration: none;
    font-size: 1rem;
    transition: color 0.3s ease;
  }
  
  .nav-links a:hover {
    color: var(--neon-purple);
  }
  

  .btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 50px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
  }
  
  .btn-primary {
    background: var(--cyber-blue);
    color: var(--space-blue);
    box-shadow: 0 0 15px rgba(0, 221, 235, 0.5);
  }
  
  .btn-primary:hover {
    background: var(--neon-purple);
    box-shadow: 0 0 20px rgba(155, 93, 229, 0.7);
    transform: translateY(-2px);
  }
  

  .hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    text-align: center;
    background: radial-gradient(circle at center, rgba(0, 221, 235, 0.2) 0%, transparent 70%);
  }
  
  .hero h2 {
    font-family: 'Orbitron', sans-serif;
    font-size: 4rem;
    margin-bottom: 1.5rem;
    color: var(--frost-white);
    text-shadow: 0 0 10px var(--cyan-glow);
    animation: fadeIn 1s ease-out;
  }
  
  .hero p {
    font-size: 1.25rem;
    max-width: 600px;
    margin: 0 auto 2rem;
    color: var(--frost-white);
    opacity: 0.9;
  }
  
 
  .courses, .lessons, .playground {
    padding: 6rem 0;
  }
  
  h2 {
    font-family: 'Orbitron', sans-serif;
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--cyber-blue);
    text-shadow: 0 0 8px var(--cyan-glow);
  }
  
 
  .grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  
  @media (min-width: 768px) {
    .grid {
      grid-template-columns: repeat(3, 1fr);
    }
  }
  

  .course-card {
    background: rgba(30, 42, 68, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 1rem;
    padding: 2rem;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .course-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 0 20px rgba(0, 221, 235, 0.3);
  }
  
  .course-card .icon {
    font-size: 3rem;
    color: var(--neon-purple);
    margin-bottom: 1rem;
  }
  
  .course-card h3 {
    font-size: 1.5rem;
    color: var(--frost-white);
    margin-bottom: 0.5rem;
  }
  
  .course-card p {
    color: var(--frost-white);
    opacity: 0.8;
  }
  

  .lessons-grid {
    display: flex;
    gap: 2rem;
  }
  
  .sidebar {
    width: 300px;
    background: rgba(30, 42, 68, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 1rem;
    padding: 1.5rem;
  }
  
  .sidebar h3 {
    font-size: 1.25rem;
    color: var(--cyber-blue);
    margin-bottom: 1rem;
  }
  
  .sidebar button {
    width: 100%;
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    background: var(--gray-dark);
    color: var(--frost-white);
    border: none;
    border-radius: 8px;
    text-align: left;
    cursor: pointer;
    transition: background 0.3s ease;
  }
  
  .sidebar button.active, .sidebar button:hover {
    background: var(--neon-purple);
    color: var(--frost-white);
  }
  
  .lesson-card {
    background: var(--gray-dark);
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 0.5rem;
    cursor: pointer;
    transition: background 0.3s ease;
  }
  
  .lesson-card:hover {
    background: rgba(155, 93, 229, 0.2);
  }
  
  .lesson-card h3 {
    font-size: 1.1rem;
    color: var(--frost-white);
  }
  
  .lesson-card p {
    font-size: 0.9rem;
    color: var(--frost-white);
    opacity: 0.7;
  }
  
  .lesson-card span {
    font-size: 0.8rem;
    color: var(--neon-purple);
  }
  
  .lesson-content {
    flex: 1;
    background: rgba(30, 42, 68, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 1rem;
    padding: 2rem;
  }
  
  .placeholder {
    text-align: center;
    color: var(--frost-white);
  }
  
  .placeholder h3 {
    font-size: 1.5rem;
    color: var(--cyber-blue);
  }
  
  .code-block {
    background: var(--gray-dark);
    padding: 1rem;
    border-radius: 8px;
    color: var(--frost-white);
    font-family: 'Roboto', monospace;
    white-space: pre-wrap;
    margin: 1rem 0;
  }
  
  .interactive-editor {
    background: var(--gray-dark);
    padding: 1rem;
    border-radius: 8px;
    margin: 1rem 0;
  }
  
  .interactive-editor p {
    color: var(--cyber-blue);
    margin-bottom: 0.5rem;
  }
  
  .interactive-editor textarea {
    width: 100%;
    min-height: 100px;
    background: var(--space-blue);
    color: var(--frost-white);
    border: 1px solid var(--cyan-glow);
    border-radius: 8px;
    padding: 1rem;
    resize: vertical;
  }
  
  .interactive-editor textarea:focus {
    outline: none;
    box-shadow: 0 0 10px var(--cyan-glow);
  }
  
  .output {
    background: var(--gray-dark);
    padding: 1rem;
    border-radius: 8px;
    margin-top: 1rem;
    color: var(--frost-white);
    font-family: 'Roboto', monospace;
    min-height: 100px;
  }
  
 
  .progress {
    margin-top: 3rem;
  }
  
  .progress h3 {
    font-size: 1.5rem;
    color: var(--cyber-blue);
  }
  
  .progress-bar {
    background: var(--neon-purple);
    height: 8px;
    border-radius: 4px;
  }
  
  .progress-container {
    background: var(--gray-dark);
    border-radius: 4px;
    height: 8px;
  }
  

  .editor {
    background: rgba(30, 42, 68, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 1rem;
    padding: 2rem;
  }
  
  #playground-code {
    width: 100%;
    height: 300px;
    background: var(--space-blue);
    color: var(--frost-white);
    border: 1px solid var(--cyan-glow);
    border-radius: 8px;
    padding: 1rem;
    font-family: 'Roboto', monospace;
  }
  
  #playground-code:focus {
    outline: none;
    box-shadow: 0 0 10px var(--cyan-glow);
  }
  

  footer {
    text-align: center;
    padding: 2rem 0;
    background: var(--space-blue);
    color: var(--frost-white);
    opacity: 0.8;
  }
  
  
  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }
  
  @media (max-width: 768px) {
    .lessons-grid {
      flex-direction: column;
    }
    .sidebar {
      width: 100%;
    }
    .hero h2 {
      font-size: 2.5rem;
    }
  }