Found this here.
LATER: From where I’m sitting, there is small and unwelcome gap just before where it says, below, “Monday 27 January 2020”. Can any passing WordPress experts explain this, and thereby help me get rid of it? (My guess is: Me asking this will cause this gap to vanish spontaneously.)
And I was right! It did vanish. And me writing the above paragraph enabled me to spot it, because the entire paragraph turned blue. A missing “/” was the problem, following the blue “here”, which, when inserted, abolished the gap. So, WordPress experts, forget about it.