How to add opacity in phonegap

Add opacity in css file with !important command

It's hard to help when we haven't seen any of your code. That said, PG doesn't change how CSS' opacity rule works, so if you aren't seeing opacity, there's something wrong with your CSS code OR you're running into a webview/platform-specific glitch.

!important shouldn't be used as a fix unless there is absolutely no other way -- !important is a pretty good sign of something wrong with the CSS in the first place (there's usually a much better way to accomplish what you need).