How to fix the problem with scrolling on the site?

Question

JavaScript

On the Opencart 2.3 template fobe4.demo.towerthemes.com/index.php?route=product... there
is a problem with scrolling. On any page other than the main page, when scrolling, the page starts to twitch when the menu should stick to the top of the browser. If you turn the mouse wheel faster, then the area skips and then scrolls normally. How can I fix this and where to look?
I wrote in support of the template developer, but they will not answer until Tuesday, and the solution is needed earlier.

Answer 1

Remove the class And you will be happy header.fix-headerdisplay: none