Simply change color of font and/or background in an existing table text or date field

Alas, there is no easy way to colorize the background of a cell as yet, like you can do with Excel Conditional formatting

But you can make a new mirror field and use this method.

https://help.quickbase.com/user-assistance/color_field.html

What about just changing the color of the font for a given field, either straight out or based on a cell value or date?

Again, you need to make a new Rich Text mirror field.

for example 

var text FontColor = 
Case([Priority],
"High","<font color=red>",
"Medium","<font color=blue>",
"Low","<font color=black>");

$FontColor & [Priority]