Why no foreground or font color with the tile backgroundcolor attribute?

So I created this DTH that picks up measured lux from a pi zero. I thought it would be nice to vary the tile color from black to bright yellow depending on the lux level, but when it gets really bright outside, the tile turns bright yellow. The value text remains white, and on the app things list, the value font color is the same as the tile background color. With a white app background the bright yellow lux value becomes unreadable. So logically I’m looking for a tile font-color attribute that is applied to the things list as well, but that does not exist? Any other ways to approach this?