body { font-family: sans-serif; margin: 20px; background-color: #f4f7f6; color: #333; }
        .container { max-width: 600px; margin: auto; background: white; padding: 30px; border-radius: 8px; box-shadow: 0 2px 10px rgba(0,0,0,0.1); }
        h1 { text-align: center; color: #2c3e50; margin-bottom: 20px; }
        .form-group { margin-bottom: 20px; }
        label { display: block; margin-bottom: 8px; font-weight: bold; color: #555; }
        select, input[type="number"] {
            width: 100%;
            padding: 12px;
            border: 1px solid #ccc;
            border-radius: 4px;
            box-sizing: border-box;
            font-size: 16px;
        }
        .submit-btn {
            background-color: #3498db;
            color: white;
            padding: 12px 20px;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            font-size: 16px;
            transition: background-color 0.3s ease;
            display: block;
            width: 100%;
        }
        .submit-btn:hover { background-color: #2980b9; }
        .message-area {
            padding: 10px;
            margin-top: 15px;
            border-radius: 4px;
            text-align: center;
        }
        .message-area.success { background-color: #d4edda; color: #155724; border: 1px solid #c3e6cb;}
        .message-area.error { background-color: #f8d7da; color: #721c24; border: 1px solid #f5c6cb;}
        .message-area.info { background-color: #d1ecf1; color: #0c5460; border: 1px solid #bee5eb;}
        .note { font-size: 0.9em; color: #777; margin-top: 10px; }