Conditional formatting: No background color when list item is selected

In my financial spreadsheet, I have the following condition. When a number is entered for a credit card charge in cell D4, cell D5 turns yellow, indicating that I have to choose an item from a drop-down list (spending category) for it. I do this by conditional formatting, yellow if D4>0.
I'm trying to get cell D5 (drop-down list) to turn back to white again when a spending category is selected. Any ideas?

Dan

It is possible by attaching two conditions to the conditional formatting.....

I have attached the screenshot......go thru

thanks

Regards,
guru

Works brilliantly, thanks! I was trying to write it by "cell value is" instead of by formulas.
I don't know how to use these conditional formulas. Where can I learn? I know this site probably has something but there's a ton of stuff to search through and it's pretty slow.

Dan