CSS does not use align: but rather text-align:
However, this applies to the contents of the element, while I suspect you are trying to make the whole box center itself in the column. The best way to do this is to add properties to the box rule for
float: none;
and
margin: auto;

The box headings are defined in the language "extra_definitions" define file described in the readme.

If by "frame" you mean the box border, you can alter the border properties in the stylesheet, or set them to border: none;