Font size relative to position in hierarchy
I would love to be able to set the font size of each level in the hierarchy to be a percentage of the parent. This could be editable in the theme customiser when it comes out.
Here I've set the parent font size to 40px and each consecutive child to be 20% of the parent's font size so:
Top level: 40px
Second level: 32px
Third level: 26px
Fourth level: 21px
Fifth level: 17px
And then a minimum font size setting so never smaller than 17px or whatever I choose.
Sixth level: 17px
Seventh level: 17px
Or if you have a large map with few levels you might want to turn it up to 30% reduction in font size per level for greater visual distinction between levels.