body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding: 0;
}

header {
    background-color: #333;
    color: white;
    padding: 1em 0;
    text-align: center;
}

#zoekbalk {
    width: 80%;
    padding: 10px;
    margin-top: 10px;
    font-size: 1em;
    border-radius: 5px;
    border: none;
}

#categorieSelect {
    padding: 10px;
    font-size: 1em;
    margin-top: 10px;
    border-radius: 5px;
    border: none;
}

#boekenlijst {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    padding: 20px;
}

.boek {
    background-color: white;
    margin: 10px;
    padding: 15px;
    width: calc(33% - 40px);
    box-sizing: border-box;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.boek img {
    max-width: 150px;
    max-height: 200px;
    object-fit: cover;
}

.boek-informatie {
    margin-top: 15px;
}

.boek h2 {
    font-size: 1.2em;
    color: #333;
}

footer {
    text-align: center;
    padding: 1em 0;
    background-color: #333;
    color: white;
}

@media (max-width: 768px) {
    .boek {
        width: calc(50% - 40px);
    }
}

@media (max-width: 480px) {
    .boek {
        width: 100%;
    }
}