Have you thought about using split

# for example:
use strict;
use warnings;
my $CSS = "";
my $filename = shift (@ARGV) || die ("No file in \@ARGV!");
open ("FILE", "< $filename")
  or die ("Cannot open $filename $!");
$CSS .= $_ while (<FILE>);
close ("FILE")
  or die ("Cannot close $filename $!");

# CSS is of the form:
# H1 { /* CSS */ }
# where H1 is the HTML element
# what's in {} is what to do
# and /* */ is comments
# so get rid of comments

$CSS =~ s[/\*.*?\*/][]sg;

# now get what's in between the {}s

my @parts = split /\}/, $CSS;
while (@parts) {
  my $part = shift (@parts);
  # now we should have CSS of the form
  # H1 { directives
  my ($HTML_element, $CSS) = split /\{/, $part, 2;
  # note that the HTML element we're working on is in
  # $HTML_element
  # now get the CSS directives
  my @directives = split ';', $CSS;
  # now each CSS directive i.e.
  # font-family: Verdana, Arial, Geneva
  # has been brokon off
  foreach my $directive (@directives) {
    my @parts = split ':', $directive;
    # $parts[0] is font-family
    my @fonts = split ',', $parts[0];
    # @fonts is all the different font families
  }
}
[download]

You'll note I did what I did because CSS states that there's a : after a property, i.e. font-family and that there are commas between different options. In any event, why not go to CPAN and pick up a ready made CSS parser? What I did was just a quick hack, and although it should give you some direction on what you can do, it almost certainly won't work nearly as well as a CPAN module -- of which there are many.