red herring or not, i bet that removing the <a > stuff fixes it
its exposing a glitch/bug in the kobo renderer , because other renderers e.g. calibre viewer are apparently Ok
the <a is somehow triggering a font change e.g. from small to normal. but its not reverting back as it should after the tag close
a class statement for the para
is shown - bodytext - but there could be other inheritance rules involved. its arguably worst CSS file I have ever seen
e.g. the <a... having no inserted class of its own , may take on the overall
body style
bodytext includes font-size: small ,
but
body does not
it's unclear because <a ... > does not introduce any rendered text
.