Can I change the look of my global header?

Yep! You have a range of style options built directly into the global header module.

While you're in the CMS editing a page, simply click the Global Header module to get into it's edit-mode.  While you're there you are going to notice style settings for two versions of the header. Standard and Sticky.

I recommend setting each of these up so that one works on a dark color background and the other works on a light color background. This is how it's configured out of the box.

In this video I'll breakdown all the other style options for you.