Can't control title size of Card Designer

Can’t control title size of Card Designer. There is no option to control the title size in the UI of Card Designer. What am I missing?

People more in the know than me will probably answer, and I’ve never used Card Designer, but I’m guessing that it might use h1,h2 or whatever tags inherited from the project settings.

The very first field in the screenshot is Lrg Title. That changes the Title. But when the Responsive option is checked it represents the maximum font-size the Title will ever be.