CSS for <sup> and <sub>

sub, sup {
  /* Specified in % so that the sup/sup is the
     right size relative to the surrounding text */
  font-size: 75%;

  /* Zero out the line-height so that it doesn't
     interfere with the positioning that follows */
  line-height: 0;

  /* Where the magic happens: makes all browsers position
     the sup/sup properly, relative to the surrounding text */
  position: relative;

  /* Note that if you're using Eric Meyer's reset.css, this
     is already set and you can remove this rule */
  vertical-align: baseline;
}

sup {
  /* Move the superscripted text up */
  top: -0.5em;
}

sub {
  /* Move the subscripted text down, but only
     half as far down as the superscript moved up */
  bottom: -0.25em;
}