Minifies the css files. Refactored code fom stackoverflow.

styles.php

<?php

if (extension_loaded('zlib')) {
	ob_start('ob_gzhandler');
}
header('content-type: text/css; charset: UTF-8');
header('cache-control: must-revalidate');
$offset = 60 * 60;
$expire = 'expires: ' . gmdate('D, d M Y H:i:s', time() + $offset) . ' GMT';
header($expire);

ob_start('compress');

function compress($buffer) {
	$cleanCSS = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $buffer);
	$gzippedCSS = str_replace(array("\r\n", "\r", "\n", "\t", '  ', '    ', '    '), '', $cleanCSS);
	return $gzippedCSS;
}

// list CSS files to be included
include('normalize.css');
include('base.css');
include('helpers.css');
include('media-queries.css');
include('print.css');
if (extension_loaded('zlib')) {
	ob_end_flush();
}