custom tooltip for header cell of grid

I am successfully getting a custom tooltip for a header cell of my grid by doing the following:

tag.title=“blah, blah, blah.”;

This works great; I get the tooltip to show up, and I also get red text in the header cell, which is what I want.

However, I need to also make the font in this particular header cell smaller, and I want to do it by using this method.

Using above works for changing the color. How can I also use to change the font?
I’ve tried a variety of possibilities, like:“12px”;
but I can’t get it to work.


Please, try to use:“12pt”;

Thank you. That worked great.