How to make the background under slideroom?

Good day, comrades. Don't understand how it's possible to implement back the grey background of the slider, if my images are jpg and they have a white background. If you replace them with png, the slider images overlap each other and looks bad. Might have to do it, if so, how? Please note that left and right are different shades of grey in the background:)
5cf278dbccc73170856961.png

Here is my code:
https://codepen.io/mal48813/pen/pmqdqO
March 23rd 20 at 18:41
0 answer

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