As we couldn't reliably reproduce this flickering issue, we needed to spend quite some time debugging it through trial and error.
The issue should now hopefully be fixed after deleting your browser's cache for forum.zorin.com, or reloading the page by pressing Ctrl+Shift+R.
If you're still experiencing this flickering, please let me know what browser, screen resolution, and OS you're using, as well as what steps you took immediately before the flickering started. This would help us to debug the issue and find a fix for it faster.