Wouldn't this semi-transparent tooltip be cool?
I know the ultimate test for any Idea is: What will this new feature allow us to do that we can't do now?* You are ultimately looking for the exciting new features, or 'big holes' your software could fill. I get that. But at some point the big features holes will start to dwindle, because you've filled most of them. And the things your users think of as holes in your product, are holes that might start to look attractive (I hope) -- especially the ones that are ultimately low-hanging fruit.
This Idea (and many other formatting requests I/we have made) are generally not 'sexy' from a developers POV, but we users beg & hope you will do a few of them each year. I hope this might be one you will consider. Thanks.
* At Tableau this question/requirement seems to have always been asked/answered from a Data Scientist's point of view. Please consider asking this same question from a Designer's point of view -- the answers will be quite different.