A demonstration should be sufficient I think.
mdoc(7) in a terminal:
... Spacing is suppressed after opening delimiters and before
closing delimiters. For example,
.Aq ( [ word ] ) .
renders as:
([⟨word⟩]).
But http://man.openbsd.org/mdoc.7 appears as:
... Spacing is suppressed after opening delimiters and before
closing delimiters. For example,
.Aq ( [ word ] ) .
renders as:
([⟨word⟩
]).
The offending HTML source (plus one line):
<div class="Bd Bd-indent">.Aq ( [ word ] ) .</div>
<p class="Pp">renders as:</p>
<p class="Pp"></p>
<div class="Bd Bd-indent">([⟨word⟩</div>
]).
<p class="Pp">Opening delimiters are:</p>
Cheers,
Matthew