/* source: problem\problem4.htm style block 1 */
body {
            font-family: Arial, sans-serif;
            text-align: center;
            margin: 20px;
        }
        h1 {
            color: #333;
        }
        .opgave {
            text-align: left;
            margin: 20px auto;
            padding: 15px;
            border: 1px solid #ddd;
            border-radius: 8px;
            width: 80%;
            background-color: #f9f9f9;
        }
        .mellemregning {
            margin-top: 10px;
            padding: 10px;
            background-color: #eef;
            border-radius: 8px;
            display: none;
        }
        img {
            width: min(320px, 80vw);
            max-width: 100%;
            height: auto;
            margin-bottom: 20px;
        }
        button {
            margin: 10px;
            padding: 10px 20px;
            font-size: 16px;
            cursor: pointer;
            background-color: #4CAF50;
            color: white;
            border: none;
            border-radius: 5px;
        }
        button:hover {
            background-color: #45a049;
        }