Hi Thor,
Your best course for this would be to target the class:
.overcalc_wrapper { }
Then add the styling for the various elements however you'd like. On a basic level, just forcing the tables to take up the full width of the page won't get them very styled. You can test this out with:
.offercalc_wrapper table {
width: 100%;
}
You'll still need to move the total around with something like:
div.offercalc_wrapper div.total_offercalc_sum {
text-align: right;
}
Then mess with the table content alignment. Here is a good quick and easy resource to help with styling: http://www.w3schools.com/css/css_table.asp
Hope that helps :)
Regards,
Devin