You can use Flex Layout (example), so something like:
<div fxLayout="row" fxLayoutAlign="center center" >
Or use these two:
Since transforms are fairly well supported now there is an easier way to do it.
<div class="cn">
<div class="inner">your content</div>
</div>
.cn {
position: relative;
width: 500px;
height: 500px;
}
.inner {
position: absolute;
top: 50%; left: 50%;
transform: translate(-50%,-50%);
width: 200px;
height: 200px;
}
.cn {
display: flex;
justify-content: center;
align-items: center;
}