When the browser window size is changed, the logo expands and shrinks along with it. How can i stop this from happening?
It resizes so it doesn't break the responsive view. I checked your site and you do have a rather wide logo, you could make an alternate mobile logo and set it here:

Style Properties -> Header and Navigation, it would switch at the XF "wide" responsive view.

Pre-Sale Questions

If you have any questions or concerns you want to ask before you make a purchase don't hesitate to use one of our multiple support channels for your convenience.