body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
}

#sidebar {
    width: 250px;
    background-color: #f4f4f4;
    padding: 15px;
    box-shadow: 2px 0 5px rgba(0, 0, 0, 0.1);
}

#content {
    flex: 1;
    padding: 20px;
}

.category {
    cursor: pointer;
    margin: 5px 0;
    padding: 5px;
    background-color: #eaeaea;
    border-radius: 5px;
}

.subcategories {
    margin-left: 20px;
    display: none;
}

.subcategory {
    cursor: pointer;
    margin: 3px 0;
}

.advert {
    margin-top: 20px;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 5px 0;
}