I am new too, trying to learn this stuff as well. Right now I am learning about javascript, in fact we only did codes in javascript to do this kind of stuff.

You can do it in CSS, but it is not recommended. You should try watching some basic javascript codes to get wanted result.

Make the class that you want to target with javascript, in your CSS and you will get a clean CSS with a nice button function.

I'd really upvote your question, but I can't since i do not have the reputation for it yet, but from my personal experience, this website is not welcoming new people trying to learn. You'll meet a bunch of old farts here, trying their best to say anything to sound smart, but not answer your question. Expamle - How to ask your question, fix your punctuation and shit... So, better go on reddit or youtube if you want your answers.

P.S. Respect for the guys who actually are trying to help you, as I've seen here in the replies.