Consider the following table (taken in part from maxima's user manual):
@multitable {greater than or equal to 333} {notequal 333} {relational function}
@headitem Operation @tab Symbol @tab Type
@item less than @tab @code{<} @tab relational infix
@item less than or equal to @tab @code{<=} @tab relational infix
@item equality (syntactic) @tab @code{=} @tab relational infix
In the pdf and info file, the columns are spaced out nicely according to the prototype. If the prototype is made wider, then the columns are wider. But this doesn't happen in the html output. The width of each column is pretty much fixed to the entry with the widest element.
But if I replace the prototype with @columnfractions, everything works nicely in info, pdf, and html.