CSS change to effect specific page template

Hello

I am trying to modify the width of the main content section for the “contact page template” of my theme but when i change this successfully in the css using ” .section{ width: XXXpx } ” … it changes for all the pages….

how do i go about making this change only for one page template and not all using php or css ?? what would be the exact code

I would greatly appreciate any help !!