:root {
            --primary-color: #1a6b4b;
            --secondary-color: #2d7f5e;
            --accent-color: #4CAF50;
            --light-bg: #f8f9fa;
            --dark-bg: #1c1c1c;
        }
        
        body {
            background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
            min-height: 100vh;
            font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
        }
        
        .brand-header {
            background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
            padding: 1.5rem 0;
            box-shadow: 0 4px 12px rgba(0,0,0,0.1);
        }
        
        .registration-card {
            background: white;
            border-radius: 20px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.08);
            border: none;
            overflow: hidden;
            margin: 2rem auto;
        }
        
        .otp-section {
            background: linear-gradient(135deg, #f8fff9 0%, #e8f5e9 100%);
            border-left: 4px solid var(--accent-color);
            padding: 1.5rem;
            margin: 1.5rem 0;
            border-radius: 10px;
        }
        
        .otp-timer {
            font-size: 0.9rem;
            color: #666;
            margin-top: 0.5rem;
        }
        
        .otp-input.is-valid {
            border-color: #198754;
            box-shadow: 0 0 0 0.2rem rgba(25, 135, 84, 0.25);
        }

        
        .otp-success {
            background: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
            padding: 10px;
            border-radius: 5px;
            display: none;
        }
        
        .otp-error {
            background: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
            padding: 10px;
            border-radius: 5px;
            display: none;
        }
        
        .btn-otp {
            background: linear-gradient(135deg, #6c757d 0%, #495057 100%);
            color: white;
            border: none;
            padding: 0.75rem 1.5rem;
            border-radius: 8px;
            transition: all 0.3s;
        }
        
        .btn-otp:hover:not(:disabled) {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(108, 117, 125, 0.3);
        }
        
        .btn-otp:disabled {
            opacity: 0.6;
            cursor: not-allowed;
        }
        
        .otp-input-group {
            max-width: 300px;
        }
        
        .otp-input {
            font-size: 1.5rem;
            text-align: center;
            letter-spacing: 10px;
            font-weight: bold;
            color: var(--primary-color);
        }
        
        .loading-spinner {
            display: none;
            width: 20px;
            height: 20px;
            border: 3px solid #f3f3f3;
            border-top: 3px solid var(--primary-color);
            border-radius: 50%;
            animation: spin 1s linear infinite;
        }
        
        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }