html {
    background-color: black;
    background-image: url('images/cityskylines3.png');
    background-size: cover;
    background-attachment: fixed;
}
    .page-header {
    background-color: #222222;
    color: #FFFFFF;
    padding: 20px;
}


}
.gallery {
    background-color: #222222;
    padding: 30px;
    width: 700px;
    margin: 0 auto;
    margin-top: 30px;
    text-align:center;
}
.gallery img {
    height: 100px;
    border-width: 5px;
    border-color: #FFFFFF;
    border-style: solid;
    box-shadow: 3px 3px 5px 6px #000000;
    margin: 5px;
}