Error with image sizing in grids

When I create divs to span across multiple cells in a grid, and then add an image and some text boxes into the the div, the images will randomly shrink to a tiny thumbnail of their correct size. They will stay like that for a while until I’ve clicked on a few things or clicked back on the parent div, and then they will suddenly go back to the correct size. Only to shrink again moments later, repeatedly and frustratingly switching back and forth between sizes for no apparent reason! Does anyone know what the heck is going on??? Please help before I lose my mind, lol.

Here is my site Read-Only:

Did you fix this? I don’t see the issue, or is it only an issue on the live site?