Finished third iteration of the theme.
Removed the height that was originally defined (and once adjusted) in pixels for the part with the datetime and amount of notes; positioning parts of the layout by specifying distances in pixels doesn't seem an all too good design anyhow. That seems to make the bar resize to fit around the text as intended.
Right-aligned the text of the "numerics" lines (Unix time number and amount of notes).
Put the amount of notes into its own line so that it has enough space despite the two longer-than-default datetime stamps.
Specified a monospaced font for the amount of notes, too.
Some source text normalisation to improve semantics/styling separation. (Not using the HTML font element; instead, div elements are used with classes and the classes are then styled in the stylesheet.)
Don't even know what the point is of documenting it like that here. Certainly the proper source history belongs in a DSCM repo eventually... sharing of that is going to be complicated though, refer to Tumblr's Terms of Service, Section 9 "Blog Themes" (Line 217) at revision 3abbdd13fd, current as of 2013-10-13T23:50Z, and specifically how it limits distribution, the lack of details on whether modification of the themes is even allowed, let alone the apparent failure to provide the so-called "free" themes under software-libre conditions.
And yes, incidentally, that is one of the ways in which tumblr is bad. And certainly something that, despite their assurances that it's only to "manage the safety and stability of blog themes" (Community Guidelines), is done in a way so that it furthers lock-in of users and content, and implements the lock-in even of mere implementations of the aesthetics. (The latter is most gratuitous because that isn't exactly part of Tumblr's business model.)
Like both of these documents mention, there's the "Theme Garden", with the Community Guidelines stressing that "anyone can host and promote their themes", but it seems that the one submission form doesn't actually publish a theme but rather submits it for Tumblr staff approval. That could arguably be fine on its own, but not with how intransparent the entire process is. No, strike that, it's a walled garden one way or another. Don't like it.
Even ignoring all that, the technical side of theming is either fairly limited or only seems so due to how badly it is documented. Eg, #timezones anyone?
Sigh. This tangent is long enough already.