Fix all edge cases caused by flexible root element for new options page

[saroyanm]

Background

After several design iterations we finally have a final version of the new options page (See #5158), but we currently are using fixed root element size.

What to change

Be sure that removing flexible root element do not cause issues in layout (e.g. buttons and tabs overflow in sidebar) and make it flexible again.

[greiner]

Are we sure that this is the expected behavior?

While the spec ​defines it as `0.3em + 13.2em + 46.3em + 0.3em`, it's unclear whether it's expected to occupy the entire space or whether we should merely center all the UI elements horizontally in which case the width would remain unchanged.

[saroyanm]

Replying to greiner:

Are we sure that this is the expected behavior?

While the spec ​defines it as `0.3em + 13.2em + 46.3em + 0.3em`, it's unclear whether it's expected to occupy the entire space or whether we should merely center all the UI elements horizontally in which case the width would remain unchanged.

I don't think that the width is the issue (if I understand your comment correctly) in this case, but I agree that we should find out final behavior of the sidebar.

The only issue currently I encounter is that the Buttons aligned to the bottom of the sidebar being overflown on the tabs which aren't aligned vertically.

[greiner]

@saroyanm Can we close this ticket? If you still think that we need to address this concern, feel free to create a GitLab issue for it instead.

[saroyanm]

So far it seems like most of the elements are responsive already, the issue mainly is with the table list, Let's followup on that here -> ​https://gitlab.com/eyeo/adblockplus/abpui/adblockplusui/issues/579#note_214895060

[greiner]

Ok, thanks. In that case I'm closing this ticket in favor of ​ui#579.