Contrast. Sometimes the theme for the daily deal is on a dark background and needs a light foreground. Sometimes the theme is on a light background and needs a dark foreground. The site toggles between the two modes.
@ahdeesan@blaineg@chienfou students do that font color prank writing papers to increase their word count to meet minimum requirements. I had one student, when I chose select all black font, who had written over and over again “I hate writing papers”. Another one had just copy/pasted something. Joke was on that student though as turnitin caught the plagiarism (which is how I even found out some students do this so knew to look in the future if the paper didn’t look nearly long enough).