Previous section visible on scroll – Home page

Good morning all, I am very happy with the CatchFullsrceen theme, however a little problem messes everything up. I tried everything myself with CSS, searching the html files and answers to my forum questions ... but I'm desperate !! On my site http://www.nanarama.fr, the images of the home page scroll incompletely (the image of the previous section and visible on the next, etc.). This was not the case on a test version carried out on http://www.mon-site-insignifiant.fr. After checking, it looks like the error is not from the CSS changes I made to it. If necessary I can send you the CSS code added on nanarama.fr or screenshots! Pleaaaase i really need your help ... Thanks in advance !!