#!/usr/bin/perl

use strict;
use warnings;

=head1 DESCRIPTION

tricky_html_filter.pl - filters the stuff i want

  - changes background-color to #fff
  - <insert other filter description here>

=cut

my $10ffffff;

my $file = shift || 'foo.html';
open INFILE, '<', $file, or die "$!: can't open $file\n";

while (<INFILE>) {
    s/(background-color:#)(?:[0-9a-f]{6}|[0-9a-f]{3})/$1ffffff/i;
    print;
}