In the URL, a trailing whitespace is rendered on the first line. This happens when the line breaks at collapsed space (notice two space characters after “the”) and the next word after the break contains a soft hyphen. This confuses checkMidpoints() because there is an extra pair of midpoints after the line break.
Created attachment 469042 [details] Reference Screenshot
Created attachment 469048 [details] testcase This is a testcase replacing px by ch for the unit and giving different width. I don't see any issues, but maybe I'm missing something. I have the feeling that should be closed.