Apologies. The word "Popup" threw me, so I didn't realise/register that you were talking about standard view tooltips.
The answer to your question is "Yes, I think so, but am not 100% sure", but, it involves you opening the main.xml file found in the specific skin folder and editing the colour values.
No, I do not have the specific colour values you'd need to edit in my head, and apologies, again, but neither do I have the inclination to go find them for you. Why? Well, that would be because, I'm 100% certain that the colours you'd need to edit would affect other colours elsewhere in your skin, and then you have a whole domino toppling effect going on, as you correct what you didn't want change and find that affects something else in turn. Colours are a nightmare
My advice to you is to find and download HPBEME's "Dream In Blue" skin. He has spent an inordinate number of freely offered hours adding comments into the main.xml file that will likely guide you as to what you need to change, and, what affects what.
Check the skin download page in the fist instance...
https://yabb.jriver.com/mediacenter/accessories.phpTo save you a little time if you want, the direct d'load link for that skin is:
https://accessories.jriver.com/mediacenter/mc_data/plugins/877.mjpGood luck in your quest
-marko