Change height of featured slider and portfolio

Hi there, Is there a way to reduce the height of the featured slider for desktop? I currently have just two lines of header text, so there is a massive amount of space above and below the copy. I have tried resizing the background image with no luck. Although the Space is fine on tablet and mobile, the desktop has significant negative space I'd like to get rid of. Similarly, I would like to reduce the height of the portfolio thumbnails on the front page... they are far too overpowering... is this possible? Thanks