SOURCE

<div class="wrap-ab">
<div class="wrap">
jeff
</div>


</div>

body,html{
    height:100%;
}
.wrap-ab{
    position:absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
}
.wrap{
    width: 100%;
    display: inline-block;
    text-align: center;
    height: 100%;
    vertical-align: middle;
    background-color: #eeeeee;
}
.wrap::before{
content:"";
display:inline-block;
height:100%;
vertical-align: middle;
}