This is called a CSS, Cascading Style Sheet.
instructions to the web browser.
IF a, then b. If not-a, then c.
Firefox! Search computer on which you find yourself.
If computer has Arial, draw page in Arial.
If no arial, search for helvetica. If you find
helvetica,user is probably on a Mac,
draw page in helvetica.
On the web, font sizes are relative, and
measured in ems.
Teeny-tiny footnote type
An interesting concept: 1.0 em means whatever is normal for the viewer, at whatever level of type zoom they are using.