Reduce the height of the front page slider

Hi
I am using BizNez Lite Theme and am wanting to reduce the height of the front page slider to approx half the size it is now – to reduce the need for scrolling on the front page. I understand I more than likely need to change the Style CSS but am unsure which part, there seems to be a lot of “slider” sections in the CSS and I have no idea what to do. What I did do was play around with it a bit and now the Normal Slider is all messed up.

Any help would be very much appreciated.
Thank you