would you please suggest me a way to eliminate the sort of shadow that is visualized on the left and top of the slider?
I can’t figure out what needs to be modified in the css file.
Well.. I do not know what you mean, but if you want to remove the border of the slider, access to -> plugins/wp-slideshow-posts/css/style-slideshow.css -> .ss1_wrapper .ss1_entry and eliminate this (in line 14):