html, body {
    font-family: Arial, sans-serif;
    margin: 20px;
    padding: 0;
    /*colorful background*/
    background: linear-gradient(135deg, #f6d365 0%, #fda085 100%);
    font-size: large;
} 

h1 {
    text-align: center;
    color: #333;
}

h2 {
    color: #555;
    border-bottom: 2px solid #ccc;
    padding-bottom: 5px;
}

fieldset {
    border: 20px solid #ccc;
    border-radius: 5px;
    padding: 15px;
    margin-bottom: 20px;
    background-color: #fff;
}

legend {
    font-weight: bold;
    padding: 0 10px;
}

form {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

button {
    padding: 10px 15px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: large;
}

.hidden {
    display: none;
}

.correct {
    border: 2px solid green;
}

.incorrect {
    border: 2px solid red;
}