10/23   In CSS (and in any other formatting sense) what does the "em" unit
        mean?  How does it convert to, say, points, picas, or mm?
        \- um it sort of depends. it can be the width of an M dep on
           font. see also "em-dash". you can google for "em-dash tex" and
           that will turns up lots of discussion. or can look in TeXbook.--psb
        \_ It's the width of an "m" as opposed to the width of an "n".