Aryeh Gregor <Simetrical+wikilist <at> gmail.com> writes:
As far as I know, the only thing actually blocking us
from doing this
was something like IE5 on Mac printing transparent images with black
backgrounds. That's probably not relevant anymore. We're still stuck
with the fact that IE6 doesn't support alpha channels, though -- we
could make the fully-transparent parts of the background transparent,
but I don't see how we could avoid aliasing effects on sane browsers
without making things look extremely ugly on IE6.
You could use PNG8 with a color palette where every color is black, with a
variable level of transparency. That would be equivalent to full PNG32 alpha
transparency in modern browsers (as long as the only color used in the formulas
is black), while IE5.5/6 would have binary transparency without any aliasing -
ugly but probably not horrible. (See
http://www.v-methods.com/ji/palette_alpha.html for a demonstration.)
Or you could just send different images to IE6, for example by using empty divs
with background images instead of img tags, and changing the image URL for IE6
with the star-html CSS hack. (Not very accessible, but maybe the text of the
formula could be written into the div with overflow:hidden?)