Slider size

Well looking at your slider – see screenshot here:
https://gyazo.com/bb86799c7d0e84e3e74cc1c784f3ae4b
I don’t see the issue?
There is no extra space padding below or above the slider images?

Please use terms like ‘width’ and ‘height’ (and not ‘thinner’ because that could be applied both ways 😉 )

I’m thinking now you want to reduce the width of the the slider to 50% of the available page width. You can do this with the following CSS:
#slider_4371 { width:50% !important; }