fix overflowing table

[benji24290]

If the table exceeds the screen width, the page gets a scroll on the x-axis. This occurs even if a parent container has 'overflow-auto' set. Adding 'position: relative' to the tableContainer resolves this issue. Not only is the scrollbar unappealing, but it also diminishes the user experience, as every date selection causes the viewport to move to the right.
Before (scrollbar on the bottom of the page):

After:

[pietsch]

I applied this fix in Nuudel. It works well and does not seem to have any negative effects on the three major browser families I tested (exemplified in my case by Librewolf, GNOME Web and Ungoogled Chromium on Linux).