:root {
            --primary-color: #0d6efd;
            --dark-bg: #1a1d20;
            --card-bg: #212529;
        }

        body {
            font-family: 'Poppins', sans-serif;
            background-color: var(--dark-bg);
            color: #f8f9fa;
        }

        /* Typography */
        h1, h2, h3 {
            font-weight: 700;
        }
        .text-code {
            font-family: 'Fira Code', monospace;
            color: #66d9ef;
        }

        /* Navigation */
        .navbar {
            background-color: rgba(26, 29, 32, 0.95) !important;
            backdrop-filter: blur(10px);
        }
        .nav-link {
            font-size: 0.9rem;
            text-transform: uppercase;
            letter-spacing: 1px;
            color: #adb5bd !important;
            transition: color 0.3s;
        }
        .nav-link.active, .nav-link:hover {
            color: var(--primary-color) !important;
        }

        /* Cards */
        .custom-card {
            background-color: var(--card-bg);
            border: 1px solid rgba(255,255,255,0.1);
            transition: transform 0.3s ease, border-color 0.3s ease;
        }
        .custom-card:hover {
            transform: translateY(-5px);
            border-color: var(--primary-color);
        }

        /* Form Validation Styles */
        .is-invalid {
            border-color: #dc3545 !important;
            background-image: none !important;
        }
        .invalid-feedback {
            display: none;
            color: #dc3545;
            font-size: 0.875em;
        }
        .is-invalid + .invalid-feedback {
            display: block;
        }