I noticed a strange behaviour in calibre 4.19 for the following situation:
In the text: both <p class="center">... and <div class="center">... are used
In the corresponding style file: Only p.center is defined but a definition of div.center is not present.
Therefore, not formatting is applied to the <div class="center"> passages.
When I use the button in the editor for removing undefined classes (my German translation uses "removing unused classes from the text", but "undefined" seems more appropriate) from the text, it does not report any undefined/unused classes in the text.
Shouldn't it remove or at least indicate that div.center is not defined? I think that previous versions did this, but I'm not sure.
Regards,
McDummy