body {
    background-color: lavender;
}
div.fill-screen {
    
    text-align: center;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    -ms-transform: translate(-50%, -50%); /* IE 9 */
    -webkit-transform: translate(-50%, -50%);
}