Featured Images in Mansory view overlapping on mobile

I have an issue with displaying portfolio images on the mobile devices. It seems to be a problem with images loading slower than site is opening, in other words site is already loaded and images slowly appearing and have no space to fit.
Problem is solved itself when mobile is flipped horisontally and then back vertically.
Is there any solution? Is it problem with gallery or theme?

The page I need help with: [log in to see the link]


This site will teach you how to build a WordPress website for beginners. We will cover everything from installing WordPress to adding pages, posts, and images to your site. You will learn how to customize your site with themes and plugins, as well as how to market your site online.

Your Advertisement Here