use Tie::Handle::Scalar;
tie *STDOUT, 'Tie::Handle::Scalar';

END
{
	my $output;
	while(<STDOUT>)
	{
		$output .= $_;
	}

	&on_finish(\$output);

	untie *STDOUT;

	print $output;
}

sub on_finish
{
    my $stdout_ref = shift;

    # Insert a stylesheet link last in the head section
    $$stdout_ref =~ s{(</head>)}{<link rel="stylesheet" type="text/css" href="/css/style.css" />\n$1}i;
}