Color a mulit-line text based on another field (mulitple choice) response.

This is actually a bit tricky to do because you were saying you have a multi line text field, and you want to colour it. The only way to colour the background is to make it a rich text formula field for display purposes, but then we have the problem that the carriage returns in a multi line select field are not recognized in a rich text formula field. So you would lose the carriage returns.  I did a test and this seems to work. But note that this would be a formula rich text field. 

var text AddLineBreaks = URLDecode(SearchAndReplace(URLEncode([multi line]), "%0A", "<br>"));

If(f ([Mulitple Choice]="No",
"<div style=\"background-color: yellow;\"" & ">" & $AddLineBreaks & "</div>", $AddLineBreaks)