Aligning sub pages to right?

I’m using the sirup theme and would like to edit it so that the pages (about etc) are aligned to the right of the page, rather than the default left.

Does anyone have any idea how to do this? I have tried absolutely everything possible I can think of to get this to work, but have had no luck. I tried editing the stylesheet ccs, and header.php adding in the alignment code in the relevant places but nothing ever changes.

Any help really appreciated.