Weird slider shadow next to image

Hi all,

I’m making a portfolio website and I added some test images and everything was fine, but this one image (Apple) shows a weird shadow of the slider next to it.

I tried removing it with CSS, but the gap between the image and the side stays. Does anyone have a solution for this?

Link: http://www.svenmannak.nl/portfolio/apple-2/