:root {
      --bg-primary: #0a0a0a;
      --bg-secondary: #111111;
      --bg-tertiary: #1a1a1a;
      --bg-glass: rgba(255, 255, 255, 0.05);
      --bg-glass-hover: rgba(255, 255, 255, 0.08);
      --text-primary: #ffffff;
      --text-secondary: #a0a0a0;
      --text-muted: #666666;
      --accent-primary: #00d9ff;
      --accent-secondary: #ff006e;
      --accent-tertiary: #8338ec;
      --accent-quaternary: #3a86ff;
      --accent-success: #06ffa5;
      --accent-warning: #ffbe0b;
      --accent-error: #fb5607;
      --border-glass: rgba(255, 255, 255, 0.1);
      --shadow-glass: 0 8px 32px rgba(0, 0, 0, 0.3);
      --gradient-primary: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-quaternary) 100%);
      --gradient-secondary: linear-gradient(135deg, var(--accent-secondary) 0%, var(--accent-tertiary) 100%);
      --gradient-success: linear-gradient(135deg, var(--accent-success) 0%, var(--accent-primary) 100%);
    }

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

    html { scroll-behavior: smooth; }

    body {
      font-family: 'Inter', sans-serif;
      background: var(--bg-primary);
      color: var(--text-primary);
      line-height: 1.6;
      overflow-x: hidden;
      position: relative;
    }

    
    .bg-animation {
      position: fixed; top: 0; left: 0; width: 100%; height: 100%; z-index: -1; opacity: 0.4;
    }
    .bg-animation::before {
      content: ''; position: absolute; top: 0; left: 0; width: 100%; height: 100%;
      background: 
        radial-gradient(ellipse 80% 80% at 50% -20%, rgba(0, 217, 255, 0.15), transparent),
        radial-gradient(ellipse 80% 80% at 20% 60%, rgba(255, 0, 110, 0.1), transparent),
        radial-gradient(ellipse 80% 80% at 80% 40%, rgba(131, 56, 236, 0.1), transparent);
      animation: gradientShift 20s ease-in-out infinite;
    }
    @keyframes gradientShift { 0%, 100% { opacity: 0.4; } 50% { opacity: 0.6; } }

    .particles { position: fixed; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; z-index: -1; }
    .particle {
      position: absolute; width: 2px; height: 2px; background: var(--accent-primary);
      border-radius: 50%; animation: float 15s infinite linear; opacity: 0.3;
    }
    @keyframes float {
      0% { transform: translateY(100vh) translateX(0) rotate(0deg); opacity: 0; }
      10% { opacity: 0.3; } 90% { opacity: 0.3; }
      100% { transform: translateY(-100px) translateX(100px) rotate(360deg); opacity: 0; }
    }

   
    .navbar {
      position: fixed; top: 20px; left: 50%; transform: translateX(-50%);
      background: var(--bg-glass); backdrop-filter: blur(20px);
      border: 1px solid var(--border-glass); border-radius: 50px;
      padding: 12px 24px; z-index: 1000;
      transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
      max-width: 90%;
      display: flex; align-items: center; justify-content: center;
    }
    .navbar:hover { background: var(--bg-glass-hover); box-shadow: var(--shadow-glass); }

    .nav-links { display: flex; list-style: none; gap: 30px; align-items: center; margin: 0; padding: 0; }
    
    .nav-link {
      color: var(--text-secondary); text-decoration: none; font-weight: 500; font-size: 14px;
      transition: all 0.3s ease; position: relative; padding: 8px 16px; border-radius: 20px;
      white-space: nowrap;
    }
    .nav-link:hover { color: var(--text-primary); background: var(--bg-glass); }
    .nav-link.active { color: var(--accent-primary); background: rgba(0, 217, 255, 0.1); }

   
    .menu-toggle { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 4px; }
    .bar { width: 20px; height: 2px; background: var(--text-primary); border-radius: 2px; transition: 0.3s; }

    
    .hero {
      min-height: 100vh; display: flex; flex-direction: column;
      justify-content: center; align-items: center; text-align: center;
      padding: 0 20px; position: relative;
    }

    .hero-title {
      font-size: clamp(3rem, 10vw, 8rem);
      font-weight: 900; background: var(--gradient-primary);
      -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
      margin-bottom: 24px; animation: slideUp 1s ease-out; line-height: 1.1;
    }

    .hero-subtitle {
      font-size: clamp(1.1rem, 3vw, 1.8rem);
      color: var(--text-secondary); max-width: 800px; margin-bottom: 40px;
      animation: slideUp 1s ease-out 0.2s both; line-height: 1.5;
    }

    .hero-cta {
      display: flex; gap: 20px; flex-wrap: wrap; justify-content: center;
      animation: slideUp 1s ease-out 0.4s both;
    }

    .btn {
      padding: 16px 32px; border-radius: 50px; text-decoration: none; font-weight: 600; font-size: 16px;
      transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1); border: none; cursor: pointer;
      display: inline-flex; align-items: center; gap: 8px; position: relative; overflow: hidden;
    }
    .btn-primary { background: var(--gradient-primary); color: var(--text-primary); }
    .btn-primary:hover { transform: translateY(-2px); box-shadow: 0 20px 40px rgba(0, 217, 255, 0.3); }
    .btn-secondary { background: var(--bg-glass); color: var(--text-primary); border: 1px solid var(--border-glass); backdrop-filter: blur(10px); }
    .btn-secondary:hover { background: var(--bg-glass-hover); transform: translateY(-2px); box-shadow: var(--shadow-glass); }

    
    .section { padding: 120px 20px; max-width: 1200px; margin: 0 auto; }
    
    .section-title {
      font-size: clamp(2.5rem, 5vw, 4rem); font-weight: 800; text-align: center; margin-bottom: 20px;
      background: var(--gradient-secondary); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
    }
    .section-subtitle { font-size: 1.4rem; color: var(--text-secondary); text-align: center; max-width: 600px; margin: 0 auto 80px; }

    /* --- CARDS & GRID --- */
    .card-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
      gap: 30px; margin: 60px 0;
    }

    .glass-card {
      background: var(--bg-glass); backdrop-filter: blur(20px); border: 1px solid var(--border-glass);
      border-radius: 24px; padding: 40px; transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
      position: relative; overflow: hidden;
    }
    .glass-card:hover { background: var(--bg-glass-hover); transform: translateY(-8px); box-shadow: var(--shadow-glass); }
    .glass-card::before {
      content: ''; position: absolute; top: 0; left: 0; width: 100%; height: 2px; background: var(--gradient-primary);
    }

    .card-icon { font-size: 3rem; margin-bottom: 20px; display: block; }
    .card-title { font-size: 1.5rem; font-weight: 700; margin-bottom: 16px; color: var(--text-primary); }
    .card-description { color: var(--text-secondary); line-height: 1.6; }

    
    .code-container {
      background: var(--bg-secondary); border: 1px solid var(--border-glass); border-radius: 16px;
      overflow: hidden; margin: 40px 0; box-shadow: var(--shadow-glass);
    }
    .code-header {
      background: var(--bg-tertiary); padding: 16px 24px; border-bottom: 1px solid var(--border-glass);
      display: flex; justify-content: space-between; align-items: center;
    }
    .code-title { color: var(--text-primary); font-weight: 600; font-size: 14px; }
    .code-copy {
      background: var(--bg-glass); border: 1px solid var(--border-glass); color: var(--text-secondary);
      padding: 6px 12px; border-radius: 6px; font-size: 12px; cursor: pointer; transition: all 0.2s ease;
    }
    .code-copy:hover { background: var(--bg-glass-hover); color: var(--text-primary); }
    .code-content {
      padding: 24px; font-family: 'JetBrains Mono', monospace; font-size: 14px;
      line-height: 1.6; color: var(--text-primary); overflow-x: auto;
    }
    .code-content pre { margin: 0; white-space: pre-wrap; }

    .keyword { color: var(--accent-secondary); }
    .string { color: var(--accent-success); }
    .number { color: var(--accent-warning); }
    .comment { color: var(--text-muted); font-style: italic; }
    .function { color: var(--accent-primary); }

  
    .terminal {
      background: var(--bg-secondary); border: 1px solid var(--border-glass); border-radius: 16px;
      overflow: hidden; margin: 40px 0; box-shadow: var(--shadow-glass);
    }
    .terminal-header {
      background: var(--bg-tertiary); padding: 12px 20px; display: flex; align-items: center; gap: 8px;
    }
    .terminal-dot { width: 12px; height: 12px; border-radius: 50%; }
    .dot-red { background: var(--accent-error); }
    .dot-yellow { background: var(--accent-warning); }
    .dot-green { background: var(--accent-success); }
    
    .terminal-body {
      padding: 24px; font-family: 'JetBrains Mono', monospace; font-size: 14px;
      line-height: 1.6; min-height: 200px;
    }
    .terminal-input {
      background: transparent; border: none; color: var(--text-primary);
      font-family: 'JetBrains Mono', monospace; font-size: 16px; /* Prevents zoom on iOS */
      width: 100%; outline: none; padding: 4px 0;
    }
    .terminal-prompt { color: var(--accent-primary); margin-right: 8px; }
    .terminal-output { color: var(--accent-success); margin: 8px 0; }

  
    .quiz-container {
      background: var(--bg-glass); backdrop-filter: blur(20px); border: 1px solid var(--border-glass);
      border-radius: 24px; padding: 40px; margin: 40px 0;
    }
    .question { margin-bottom: 30px; }
    .question-title { font-size: 1.2rem; font-weight: 600; margin-bottom: 20px; color: var(--text-primary); }
    .option {
      background: var(--bg-secondary); border: 1px solid var(--border-glass); border-radius: 12px;
      padding: 16px 20px; margin-bottom: 12px; cursor: pointer; transition: all 0.3s ease;
      display: flex; align-items: center; gap: 12px;
    }
    .option:hover { background: var(--bg-tertiary); border-color: var(--accent-primary); }
    .option.selected { background: rgba(0, 217, 255, 0.1); border-color: var(--accent-primary); color: var(--accent-primary); }
    .option.correct { background: rgba(6, 255, 165, 0.1); border-color: var(--accent-success); color: var(--accent-success); }
    .option.incorrect { background: rgba(251, 86, 7, 0.1); border-color: var(--accent-error); color: var(--accent-error); }
    .radio {
      width: 20px; height: 20px; border: 2px solid var(--border-glass); border-radius: 50%; position: relative; flex-shrink: 0;
    }
    .radio.selected::after {
      content: ''; position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);
      width: 10px; height: 10px; background: var(--accent-primary); border-radius: 50%;
    }

    @keyframes slideUp { from { opacity: 0; transform: translateY(50px); } to { opacity: 1; transform: translateY(0); } }
    .fade-in { opacity: 0; transform: translateY(30px); transition: all 0.6s ease; }
    .fade-in.visible { opacity: 1; transform: translateY(0); }
    
    .progress-bar {
      position: fixed; top: 0; left: 0; width: 0%; height: 3px; background: var(--gradient-primary);
      z-index: 1001; transition: width 0.1s ease;
    }

  
    @media (max-width: 768px) {
      .navbar {
        left: auto;          
        transform: none;     
        right: 20px;
        width: 50px; height: 50px; 
        border-radius: 50%; padding: 0;
        flex-direction: column; overflow: hidden;
      }
      
    
      .navbar.active {
        width: 90%; height: auto;
        border-radius: 24px;
        padding: 20px 20px 30px 20px;
        background: rgba(10, 10, 10, 0.95); 
      }

      .menu-toggle { display: flex; z-index: 2; }
      
      
      .nav-links { 
        display: none; 
        flex-direction: column; 
        width: 100%; 
        gap: 20px; 
        margin-top: 20px; 
        opacity: 0;
        transition: opacity 0.3s ease;
      }
      
      .navbar.active .nav-links {
        display: flex;
        opacity: 1;
      }
      

      .navbar.active .bar:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
      .navbar.active .bar:nth-child(2) { opacity: 0; }
      .navbar.active .bar:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

      .nav-link { font-size: 16px; padding: 10px; display: block; text-align: center; }
      
      .hero { padding: 120px 20px 60px; }
      .hero-cta { flex-direction: column; width: 100%; align-items: center; }
      .btn { width: 100%; max-width: 300px; justify-content: center; }
      .section { padding: 80px 20px; }
      .card-grid { grid-template-columns: 1fr; gap: 20px; }
      .glass-card { padding: 24px; }
    }