prefix CSS classes generated by the MMT presenter and make custom CSS

For instance for a constant declaration, the MMT presenter generates

<div class="constant">
   <span class="keyword">constant</span>
   <span class="name" data-mmt-symref="http://mathhub.info/MiKoMH/GenCS/SML/en/SML-IO-fail.omdoc?SML-IO-fail?" id="SML-IO-fail?"></span>
    <span data-mmt-symref="http://cds.omdoc.org/urtheories?Informal?opaque">
    <span class=" ltx_tag_itemize">•</span>
 </span>
</div>

And this has CSS classes from various sources. LaTeXML prefixes its classes, so that we can distinguish them. OMDoc sometimes does as well (I am assuming some of them are copied over), but MMT does not.

I would like to see

prefixes (as indicated in the title), e.g. something like mmt_ or mmtpres.
a CSS stylesheet mmtpres.css that gives default values for all these classes (and only these), this should also be integrated into MathHub.info in the relevant places.
Then I can cascade and override this in smglom.css and gencs.css (see https://github.com/KWARC/MathHub/issues/148). Assigning to @m-iancu, but @cmaeder might also be interested.

UniFormal / MMT

prefix CSS classes generated by the MMT presenter and make custom CSS #90