body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    text-align: center;
    background-color: #f8f8f8;
}
header {
    background: #333;
    color: #fff;
    padding: 15px;
}
.listings {
    display: flex;
    justify-content: center;
    gap: 20px;
    padding: 20px;
}
.ad {
    background: #fff;
    padding: 15px;
    border-radius: 5px;
    box-shadow: 0 0 5px rgba(0, 0, 0, 0.2);
}