--file-margins css var could be split

[daledesilva]

As a developer, I'm trying to make sure my visual elements line up with the horizontal margins of the text in the note.
To do this, I'm using something similar to the below (but it could equally be padding-right or margin-inline, etc.

right: var(file-margins, 5%);

This works on desktop because file-margins is defined as var(--size-4-6), however, on mobile it fails but doesn't trigger the fall back because file-margins is now given 2 values: var(--size-4-2) var(--size-4-6)

These values will change depending on the theme and therefore file-margins is not usable unless you're using explicitly on something that can take margin on all 4 sides.

This may well be the purpose of file-margins, however, it leaves there no way to use an individual margin value if needed (Either in a plugin or theme).

I'd propose adding 2 or 4 more variables so that the definitions could be:

--file-margin-block: var(--size-4-2);
--file-margin-inline: var(--size-4-6);
--file-margins: var(--file-margin-block) var(--file-margin-inline);

That way devs could utilise logical values without breaking anything existing.