Dumb clutch fluid reservoir question

HOW DO I GET THE DAMN CAP OFF???

I need to add a drop or two of hydraulic fluid to the clutch fluid reservoir and I can't get the cap off. I have tried unscrewing it -- it won't turn -- maybe Godzilla put it on hand-tight or something. I tried gently prying it off. Nothing doing.

How does it come off -- unscrew or pry up?

Add DOT3 brake fluid, right??

Thanks.