jumping menu options

Hi, a strange thing is happening with my menu options. When I click on an option, the first three options on the menu jump a very little to the left and then settle back where they were in their original location. It is only the first three options, not all the options.

I’ve checked some other sites using the Hatch theme and it happens on their sites too. Is this supposed to happen with this theme?

How can I make it so all the options jump to the left, or none of them jump? My dev area is https://www.jgdigital.co.uk/stovold/

https://www.ads-software.com/extend/themes/hatch/