body {
            font-family: Arial, sans-serif;
            text-align: center;
        }
        canvas {
            border: 2px solid black;
        }
        button {
            margin: 10px;
            padding: 10px 20px;
            font-size: 16px;
            cursor: pointer;
        }
        #popup {
            display: none;
            position: fixed;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            background: white;
            padding: 20px;
            border: 2px solid black;
            box-shadow: 0px 0px 10px gray;
            z-index: 1000;
        }
        #popup button {
            margin-top: 10px;
        }
        #overlay {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.5);
            z-index: 999;
        }