Disable slide in effect

Hi folks,

Maybe one of you has an idea here .. when I scroll down, the menu appears sliding, but when I scroll up, this effect shouldn’t be visible in my opinion.

At this moment it looks like the menu-bar jumps to the top instead of sliding.

You could check / test it on http://hielke.net/feenstra

Thank you in advance 🙂

https://ww.wp.xz.cn/plugins/mystickymenu/