sometimes make editor bigger

[fbstj]

this is a bit of a brain dump from me, feel free to ignore

the editor window is sometimes fairly crammed in. I was going to suggest resizing the text-box, but I tested it and it seems to do that already. looking at it though there's a lot of "wasted" space, which I don't see as adding anything:

I don't think the edit page should come with the full-height header, nor does it seem sensible to have so much white-space around every element even in the small-header variant:

for me, at least, the double-scroll-bar effect is counter-productive when I only want to be looking at all the stuff that's in the inner-pane.

the horizontal layout is ok, I have no problem with the 'fixed-width' & centered view.

If I'm in the big-header variant (scrolled to top of page) I can scroll the inner pane to it's bottom but I don't see the bottom of the content.

• it would possibly be better if the audio player was fixed/floating/sticky: either along the bottom, or at least less than 30vh
• the save button should possibly be more highlighted
• the add-another button is maybe redundant when editing existing?
• the url-source (table) & footnotes (editor) rows should possibly be invisible if empty, and give an orange button to "+ add footnote" and "+ add url source". they each currently take up minimum 3-4 lines of space even when empty
• the url-sources editor should maybe be split out or made into just a display + an edit dialogue instead of inline in the bottom.
• if the snippet stuff is stuck to the bottom, the url-sources could be generalised to include the information & edit interface for the snippets and images (if necessary, see image sources have missing edit ui #49)