html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    display: table;
    background-color: black;
}
.container {
    display: table-cell;
    text-align: center;
    vertical-align: middle;
}
.content {
    display: inline-block;
    text-align: left;
}