Prevent Overlapping Elements and Correct Z-Index

[grabinskij]

Resolve any instances of overlapping elements within the header and ensure the z-indexes of all elements are properly adjusted.
AC:

• resolve any instances of overlapping elements within the header;
• ensure the z-indexes of all elements are properly adjusted.

[006080]

I’m not completely in agreement with the shadow implementation you used in the Header. I’ve opened a new ticket #266 to address this and will work on refining it. The shadow should be applied to the CategoriesTab component and should appear on the scroll, fixing itself at a specific point.

[grabinskij]

I am closing this ticket because a better solution has been found.

[grabinskij]

I reopened this ticket because I found additional issues that need to be improved