How to change contact form size?

Hi guys, sorry in advance if this is the wrong section to be posting in.

I have been trying to add a simple email contact form to my revolution slider and for some reason the form is way too big. I have no idea on how to make it a more manageable size. I did some google searching and people are saying to do something to the css style sheet but I think my theme is not allowing me to change the size. I am not experienced with css but what I am trying to do should be simple in theory, should it not?

Thanks in advance for the help!

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