body {
            font-family: 'Courier New', monospace;
            background-color: #121212;
            color: #0f0;
            max-width: 900px;
            margin: 0 auto;
            padding: 20px;
        }
        .header {
            text-align: center;
            border-bottom: 1px solid #333;
            padding-bottom: 20px;
        }
        .challenge {
            background-color: #1a1a1a;
            padding: 15px;
            margin: 20px 0;
            border: 1px solid #333;
            border-radius: 5px;
        }
        .flag-input {
            background-color: #121212;
            color: #0f0;
            border: 1px solid #0f0;
            padding: 8px;
            width: 300px;
        }
        .submit-btn {
            background-color: #0f0;
            color: #121212;
            border: none;
            padding: 8px 15px;
            cursor: pointer;
            font-weight: bold;
        }
        .hidden {
            display: none;
        }
        .completion-message {
            text-align: center;
            margin-top: 30px;
            padding: 20px;
            background-color: #1a1a1a;
            border-radius: 5px;
            border: 1px solid #0f0;
        }
        .professional-btn {
            background: linear-gradient(135deg, #6e8efb, #a777e3);
            color: white;
            border: none;
            padding: 12px 24px;
            font-size: 16px;
            border-radius: 30px;
            cursor: pointer;
            margin-top: 20px;
            font-weight: bold;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
            transition: all 0.3s ease;
        }
        .professional-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
        }
        .ranking-container {
            background-color: #1a1a1a;
            padding: 15px;
            margin: 20px 0;
            border: 1px solid #333;
            border-radius: 5px;
        }
        .ranking-table {
            width: 100%;
            border-collapse: collapse;
        }
        .ranking-table th, .ranking-table td {
            padding: 8px;
            text-align: left;
            border-bottom: 1px solid #333;
        }
        .ranking-table th {
            background-color: #0a0a0a;
        }
        .question {
            margin-bottom: 10px;
        }
        .options {
            margin-left: 20px;
        }
        .binary-answer {
            font-family: monospace;
            letter-spacing: 2px;
        }