* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    color: #333;
}

header {
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
}

#book-promo {
    display: flex;
    justify-content: space-around;
    align-items: center;
    margin: 50px auto;
    max-width: 1000px;
    padding: 20px;
}

.book-info {
    max-width: 500px;
}

.book-cover img {
    width: 250px;
    height: auto;
    border-radius: 10px;
}

#download-section {
    text-align: center;
    margin-top: 40px;
}

button {
    background-color: #5cb85c;
    color: white;
    padding: 15px 25px;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    cursor: pointer;
}

button:hover {
    background-color: #4cae4c;
}

#thank-you-message {
    margin-top: 20px;
    font-size: 18px;
    color: #5cb85c;
}

.hidden {
    display: none;
}

footer {
    text-align: center;
    padding: 20px;
    background-color: #333;
    color: white;
    margin-top: 50px;
}