TeXmacs and HTML
In this article we discuss question related to conversion from/to HTML.
Since TeXmacs 1.99.14 we support an improved converter to HTML.
The new converter is stylable using CSS, which
should allow you to produce nice web versions of your papers that are
readable on multiple devices. Joris' personal website shows what you can
do: https://www.texmacs.org/joris/main/joris.html
For a random math paper, see: https://www.texmacs.org/joris/ffnlogn/ffnlogn.html
The precise CSS style can be selected in the user
preferences dialog: →→→.
If someone with CSS design skills wants to
contribute other styles, then we would be happy to include them in the
official distribution.
Note that TeXmacs can both export formulas as MathML
as well (as noted in the discussion) and as MathJax
(not clearly mentioned so far).
It should be noted that both MathML and MathJax come with their problems (and that is why a
prefer the less errorprone solution of images):

Both the rendering quality of MathML and
MathJax is not as good as with TeXmacs

MathML lacks support for formula integration in the main text. For
instance, equation arrays are a pain. Joris found a way to hack this
with CSS in the case of images, but MathML is not sufficiently widely used for
duplicating this effort.

MathJax lacks several LaTeX constructs, so the
standard LaTeX export filter would need to be hacked quite a bit for
various exotic constructs and we don't have currently enough
developer time and energy for doing the LaTeX export filters twice.
Concerning copy&paste, we might annotate images with LaTeX formulas.
That would not be very hard to implement, although it would take some
time, of course.