Mathjax still does not support automatic breaking on long equations. I do not think it will ever do that.
Currently tex4ht even when using svg (i.e. image for math, and not mathjax), it does not support breqn package. This means long equations look bad in HTML since they exceed the width of the web page. If tex4ht, using SVG for math, could generate images of the equations the same as it looks in pdf with breqn, this will make the pages look much better. These equation are auto-generated from CAS systems and not possible to manually breaking them each time and many of them can be long. CAS system do not break long equations themselves when they emit the Latex. I was wondering how hard it will be to have tex4ht support fully the breqn package directly? i.e. generate same math as that in PDF for long equations (but in svg mode). Thanks --Nasser
