I'm quite sure it's not possible from within Google Calendar itself. Google never gives you many possibilities in editing their interfaces.
What would be possible to to make a CSS user script and edit the design by hand.
Try this Chrome Extension: Minimalist for Google Calendar™
It adds a number of options to modify the interface of Google Calendar. It also has a method for inserting custom CSS. Although I think editing Google's CSS code would be quite hard, if you're a little experienced with you can give it a try, I think you will figure out soon enough weither or not you have a chance to succeed.