Columns misaligned

Hi,
I have a gallery that has mostly pictures in it that link to a different page or attachment. I now, for the first time, wanted two thumbnail that don’t link anywhere, and used your suggested “[none]”in the link field. It works, but unfortunately these two thumbnails are slightly out of line with the other thumbnails. Please check this link to see what I mean: https://www.travelintense.com/publications (I’m talking about ‘Aston Martin Magazine’ and ‘Unterwasser’ at the very bottom of the page).
Could you please tell me how to correct this design flaw?
Cheers,
Michaela