let the browser use the font the user has set up
as the default fixed-width font, instead of forcing Courier.

also set the size to 100%, which means 100% of the
font size in the surrounding text.  this looks a little
better in the main body but much better when the
code is in a heading (like Package unsafe).

R=r
DELTA=4  (1 added, 0 deleted, 3 changed)
OCL=34947
CL=34947