Bad news and good news…..First the bad: To design a menu like that in place of the existing one for Celestial, that would actually require a complete recode (redesign) of the menu, and would not be a quick coding project. You could look at the source code for the chrome.min.css file from that link you sent me for their menu navigational css, but the problem is to implement that into a WP theme as it won’t be a small quick job to do. The good news is that I could do that for you but then this becomes billable time (which perhaps this part is also bad news).
**By the way, I just created this new forum “General Topics” for this one because the Suggestion forum was not the right category, nor was a specific theme forum. So now this new forum can now be used for generalized topics 🙂