html,body {
    display: table;
    width: 100%;
    height:100%;
    background-image:linear-gradient( to bottom, #111, #333 );
 }
body {
    display: table-cell;
    vertical-align: middle;
 }
main {
    position: relative;
    max-width: 48em;
    margin: auto;
    border: 1px solid #69605f;   
 }
video {
    display: block;
    width: 100%;
    height: auto;
 }
img {
    position: absolute;
    top: 1.25em;
    left: 1.25em;
 }