Drag and Drop colours

How can I change the colour of the droppable text boxes in Drag and Drop exercises? I used to be able to do that but now I can't remember how it's done!

Summary: 
Drag and drop colours
Content types: 
BV52's picture

Hi finkingcap,

Afaik the only way to change the color of the text box is to change the highlight of the text (screenshot attached).

-BV52