Responsiveness for images in grid

I wish to fix the responsiveness of my pictures when switching to anything narrower than desktop(tablet,mobile,etc), as currently, the container seems to be overflowing outside of the viewport and thus the pictures are overflowing.

It is supposed to be responsive on narrower viewports, as such:

What my work looks like, container and images overflowing on anything narrower than desktop:

Here is my site Read-Only:

Here is the Read-only of the template from which im basing myself on: