This is easy and very short:
.block {_x000D_
display: table-row;_x000D_
vertical-align: middle;_x000D_
}_x000D_
_x000D_
.tile {_x000D_
display: table-cell;_x000D_
vertical-align: middle;_x000D_
text-align: center;_x000D_
width: 500px;_x000D_
height: 100px;_x000D_
}
_x000D_
<div class="body">_x000D_
<span class="tile">_x000D_
Hello middle world! :)_x000D_
</span>_x000D_
</div>
_x000D_