Hi Nasser,
> breqn is only needed in pdf mode due to limited page width > and not in HTML mode. tex4ht does not support breqn, which is OK, > as not really needed for HTML. > I think we should really support breqn, I've tested it in the MathML and image math modes and it failed with fatal error. So this is something that we really should fix. > > So all the equations are duplicated everywhere. It will be > great to be able to just write the dgroup or dmath parts only, > and have tex4ht automatically convert them to use align > internally (may be using macro or lua code?). Yes, this isn't really nice. I posted Lua based solution to TeX.sx: https://tex.stackexchange.com/a/620138/2891 > Is the above possible to do by any chance without a very great > effort and time? Or there is something technically which would > this translation not possible to do at run time? The Lua code can be easily modified to support more environments. In other modes than MathJax, it will be probably more difficult, as it seems that Breqn clashes heavilly with TeX4ht. I haven't looked at the sources yet, so I don't know how serious it is. Best regards, Michal