use image as button in header?

In 7.1, I have a button in the header with a link to another website. I don't see a way to replace the button with an image that will still link to the website. Can that be done?

You can use CSS to set background image

or CSS to replace button with image

Difficult to help without site url.

Thanks. The site is not public yet but it should be in about a week. I am not a coder so I was hoping that ability was built into squarespace.