How to set a background-image for a slider?

Question

css

How can the slider make a background in the form of such an image https://cdn1.savepice.ru/uploads/2020/4/10/b5c41e7... and make this image adaptive along with the slider (that is, adjust to its size)?
I uploaded the code here https://codepen.io/marishik92/pen/KKdwPgX I tried to use both background-image and mask for the banner__slider
block in css, but nothing works

and not put as a frame that is placed outside the block.