So after looking at some of the spec rules for #10017, I'm concerned that dividing (in calc()) by values with percentages produces inconsistent results. The rules for invert invert (and preserve) percent types but erase percent hints. This means when a percentage in the divisor leads to it having a "percent" type it is preserved, but when it leads to a percent hint, it is removed. For example this means that calc(30px / 20%) has a type that involves percentages whereas calc(30px / (20% + 10px)) does not. This seems wrong, and it seems like inverting a type should preserve the percent hint rather than erasing it.