How to change Grand Total font weight?

in the SO the “Grand Total” field is bold and big. Where can i change it to normal font weight? Since print format builder has not the ability to change things like that. So i want to change it hardcodet in the in the files.

Any suggestions where i should look or how to change it?
The server path to the folder would be appreciated.

solved it!
normal font stile and normal font size.

it is possible to overwrite the css with the print format builder. changed this css code by entering in the css field:

.important .value {
font-size: 100%;
font-weight: normal;

hope this helps someone who has the same idea for b2b SO.