Images randomly resizing

These images are resizing when viewing the page, from regular size to very tiny. I am not sure why. I have tried creating a new section and new div and re-adding the image. But somehow it still is fluctuating between proper and improper size.

How can I resolve this?

Intended image size:

Incorrect image size:

Here is my site Read-Only: read only link
([how to share your site Read-Only link][2])