Opera 7.54u1, 8 and 9 Preview 2 show a different dotted border style depending on the length of the text styled. This can be shown clearly by the lines below. Note how the last line is the same as the line above it, except for an additional space at the end of the text. Yet the border style is different.
A.
AB.
ABC.
ABCD.
ABCDE.
ABCDE .
'Francky' has also made a superb demo about this bug: Opera: dotted border bug and workarounds.
Devised by Chris Hester 24 January 2005. Last updated: 5 October 2016.