Resizing problem

Helo,
Thank You for great and powerfull plugin!

Please look at this address https://c36.hekko24.pl/fullpage/fullpage1/
Try resizing the browser window – size of white div changing its size randomly.

I need that this white box fill entire vieport with few % margin around.

What em I do wrong?
Thank for Your time
Peter

https://www.ads-software.com/plugins/wp-fullpage/