More Frontend QA Polish Changes

[emma-sg]

Sort of relevant to #1696

• Improves a number of layout elements at smaller viewport sizes (specifically, letting button groups wrap onto next lines & ensure titles can't shrink to 0 width)
• Adds "No page title" to places where there'd normally be a page title but isn't
• Applies grid styling to page list area to fix overflow issues
  • When selecting or loading with a page selected that's farther down on the page list, the top of the page header could be scrolled away from, and there'd be no way to scroll back because the area had overflow: hidden applied
• Adds default width and height to image comparer element, so that it displays correctly when images haven't loaded and doesn't change layout when images load

[Shrinks99]

On the train RN but ran into some layout issues with the new grid area layouts. Can expand later but wanted to flag.

[emma-sg]

@Shrinks99 this should be fixed with 11f8f46!

[Shrinks99]

Table row cells are a bit large now haha

Everything else looks good!!

[emma-sg]

Oh I fixed that but I did so here instead of this PR whoops! just a sec

[Shrinks99]

Ah no worries then, reviewing out of order! :)