Hello, @admin@kitalabel.com,
I have checked your site on the 1920×1080 px resolution and the issues you have mentioned are not appear. Check this video first: Under Private Content Area
You can clearly see in the video the button and the sticky header work fine. There is no issue as you described. Please once clear your browser cache and check back to your site again I hope you will never face the issues again.
Regards 8Themes Team.