{literal}
<style>
TABLE.nwaContent, DIV.nwaContent, TH.nwaTop, DIV.nwaTop, TH.nwaLeft, TABLE.nwaContent TD, TH.nwaBottom, DIV.nwaBottom, button, input[type="submit"] {
padding: 0px;
margin: 0px auto;
width: 350px;
}
</style>
{/literal}
This will center everything within the box when you add it in the Register UI header