.difficulty-selector {
            display: flex;
            justify-content: center;
            gap: 10px;
            margin-bottom: 20px;
        }
        
        .diff-btn {
            padding: 10px 15px;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            font-weight: 600;
            transition: all 0.3s;
        }
        
        .diff-btn.easy {
            background: #28a745;
            color: white;
        }
        
        .diff-btn.medium {
            background: #ffc107;
            color: black;
        }
        
        .diff-btn.hard {
            background: #dc3545;
            color: white;
        }
        
        .diff-btn.active {
            transform: scale(1.1);
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
        }
        
        .captcha-container {
            margin: 20px 0;
            padding: 20px;
            background: #f9f9f9;
            border-radius: 10px;
            border: 1px solid #ddd;
            position: relative;
            overflow: hidden;
        }
        
        .captcha-display {
            font-size: 32px;
            font-weight: bold;
            padding: 20px;
            margin: 15px 0;
            background: linear-gradient(45deg, #eee, #fff);
            border-radius: 8px;
            box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.1);
            color: #333;
            text-shadow: 2px 2px 0 #fff, 1px 1px 0 #ccc;
            position: relative;
            overflow: hidden;
        }
        
        .captcha-display::before {
            content: "";
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: repeating-linear-gradient(
                45deg,
                rgba(0, 0, 0, 0.05),
                rgba(0, 0, 0, 0.05) 5px,
                transparent 5px,
                transparent 10px
            );
            pointer-events: none;
        }
        
        .captcha-controls {
            display: flex;
            justify-content: center;
            gap: 10px;
            margin: 15px 0;
        }
        
        .captcha-btn {
            padding: 12px 20px;
            background: #4a90e2;
            color: white;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.3s;
            flex: 1;
        }
        
        .captcha-btn:hover {
            background: #357abD;
            transform: translateY(-2px);
            box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
        }
        
        .captcha-btn.refresh {
            background: #6c757d;
        }
        
        .captcha-btn.refresh:hover {
            background: #5a6268;
        }
        
        .form-group {
            margin: 20px 0;
            text-align: left;
        }
        
        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: #444;
        }
        
        input[type="text"] {
            width: 100%;
            padding: 14px;
            border: 1px solid #ddd;
            border-radius: 8px;
            font-size: 16px;
            transition: border-color 0.3s;
        }
        
        input:focus {
            border-color: #4a90e2;
            outline: none;
            box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.2);
        }
        
        .submit-btn {
            background: linear-gradient(45deg, #1a2a6c, #b21f1f);
            color: white;
            border: none;
            border-radius: 8px;
            padding: 15px;
            width: 100%;
            cursor: pointer;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.3s;
            margin-top: 20px;
        }
        
        .submit-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
        }
        
        .message {
            padding: 15px;
            border-radius: 8px;
            margin: 20px 0;
            text-align: center;
            font-weight: 600;
        }
        
        .error {
            color: #dc3545;
            background: #ffebee;
            border-left: 4px solid #dc3545;
        }
        
        .success {
            color: #28a745;
            background: #f0fff4;
            border-left: 4px solid #28a745;
        }
        
        .captcha-stats {
            display: flex;
            justify-content: space-between;
            margin-top: 15px;
            font-size: 14px;
            color: #666;
        }
        
        .usage {
            margin-top: 25px;
            padding: 15px;
            background: #fff3cd;
            border-radius: 8px;
            border-left: 4px solid #ffc107;
            text-align: left;
        }
        
        .usage h3 {
            color: #856404;
            margin-bottom: 10px;
        }
        
        .usage code {
            display: block;
            background: #fff;
            padding: 10px;
            border-radius: 5px;
            margin: 10px 0;
            font-family: monospace;
            overflow-x: auto;
        }
        
        .hint {
            color: #6c757d;
            font-size: 14px;
            margin-top: 5px;
        }