Page / Text sliding up and down

Hi
Readers of the page run into very awkward disconformt for their eyes when looking at the pages with built in image gallery. Because not all images have exactly the same size the following problem occurs:

What trick can I apply to prevent the whole page from moving up / down as the images are changing? I do not want to change the size of the images though.

see example:
https://www.cleverways.ch/new-reality/

thx much and kind regards,
charles