Set Widget Boxes All The Same Size

So my website is here

[URL=”http://www.graceleepromotions.com/handdiagnosis/”]http://www.graceleepromotions.com/handdiagnosis/[/URL]

There are 3 boxes on the home page and then 4 boxes underneath which also show on all the pages.

I want to manually set the code so that the boxes do not shrink or enlarge when content inside them is different length.

I want the boxes to allways be the same size as each other.

How?

Thanks!