Any way to stop Drupal css from dynamically resizing pages?
You need to add some css to various places in your theme, then. Give a 'width' attribute to the divs that contain the pieces of your page.

You may also be interested in 'min-width' and 'max-width' attributes.

Check out the drupal theming guide, or better yet, the README in your active theme's folder, to learn where and how to add the css. You don't have to be an expert- with just a little bit of time, this should be pretty easy.