The other day a customer considering Sticky wrote me a great question:
Will Sticky use my theme settings for the color of the add to cart bar?
Sticky will automatically detect and use your add to cart button design.
For example, if you have a green button with white text, it will use that.
If it says "Add to Bag" instead of "Add to Cart", it will use that.
If you change your add to cart button design in your theme, Sticky will change too.
The whole point of Sticky is to be unobtrusive, which is why it mimics your existing design as much as possible.
It shouldn't look like mismatched app that was installed. It should be a well-designed and matching component of your product page.
Eric Davis