Why does the site jump when clicking on menu links?

Question

Joomla

There is a site made in joomla (if that matters). Here is the site sovmed.ru.
When you go through the menu items, the site jumps. Maybe it's being redrawn, maybe something else, I don't know, but here's the problem. I do not like it. Can anyone suggest what's wrong?

Answer 1

Strange, there were answers, where did they disappear to?