body {
            font-family: Arial, sans-serif;
            margin: 0;
            padding: 0;
            background-color: #f4f4f9;
        }
        .container {
            max-width: 800px;
            margin: 10px auto;
            background: #fff;
            padding: 5px;
            border-radius: 8px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        }
        h2 {
            text-align: center;
            color: #333;
        }
        form {
            display: flex;
            flex-direction: column;
        }
        label {
            margin-bottom: 5px;
            font-weight: bold;
        }
        input, textarea, button {
            margin-bottom: 15px;
            padding: 10px;
            border: 1px solid #ccc;
            border-radius: 5px;
            font-size: 16px;
        }
        input:focus, textarea:focus {
            border-color: #007BFF;
            outline: none;
        }
        button {
            background-color: #007BFF;
            color: #fff;
            border: none;
            cursor: pointer;
        }
        button:hover {
            background-color: #0056b3;
        }
.melding {
    display: none;              
    background: #fff3cd;        /* zacht geel */
    color: #856404;             
    padding: 15px;
    border: 2px solid red;      
    border-radius: 5px;
    margin-bottom: 20px;
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
}
.melding.show {
    display: block;
    opacity: 1;
}
input:invalid, textarea:invalid {
    border: 2px solid red !important;
    background-color: #ffe6e6;
}
input:focus:invalid, textarea:focus:invalid {
    border: 2px solid red !important;
    outline: none;
}