The property, I think, makes for example dark text color on light background if it is set to be light and text cannot be read...or reverses text color if it is on image and/or vice versa.
I've seen some questions on SO with it but really can't find them anymore and dont remember property name. In case I am unclear:
If text color would be set to white, we couldnt read it because python logo has some white space around it and text is over image. There is a css property which would set text to black as it is now. What is its name?