A simple PHP function that take an array of CSS values and puts them into relevant media queries

gistfile1.php

<?php
function parseCss($css = array()) {
  // Init
  $return = array();

	// Set the break points here
	$return['default'] = '';
	$return['tablet'] = '@media only screen and (max-width : 1024px) {';
	$return['phone'] = '@media only screen and (min-width : 320px) and (max-width : 480px) {';

	// Loop and append
	foreach ($css as $css_key => $css_value) {
		$return['default'] .= $css_key . '{';
		if (is_array($css_value)) {
			foreach ($css_value as $ak => $av) {
				if (is_array($av)) {
					$return[$ak] .= $css_key . '{';
					foreach ($av as $k => $v) {
						$return[$ak] .= $v . ';';
					}
					$return[$ak] .= '}';
				} else {
					$return['default'] .= $av . ';';
				}
			}
		} else {
			$return['default'] .= $css_value . ';';
		}
		$return['default'] .= '}';
	}
	
	// @TODO - make this so you don't have to update everytime you add a breakpoint
	return ($return['default'] . $return['tablet'] . '}' . $return['phone'] . '}');
}


/*
* USAGE
*/

// variables
$blue = '#009';

// mixin -- kind of a hack, since duplicate keys can't be added in array
$border = array (999999 => 'border: 2px solid #676');

$css = array (
	'h1, h2, h3' => 'color: #449',
	'#content' => array (
		'width: 800px',
		'margin: 0 auto',
		'background: #dd9',
		'tablet' => array (
			'background: red',
		) + $border,
		'phone' => array (
			'background: ' . $blue,
			'width: 100%',
			'border: 2px solid #090',
			'color: #fff'
		),
	),
	'a' => array (
		'color: #069',
		'text-decoration: none'
	),
	'a:hover' => array (
		'text-decoration: underline'
	),
);

// If you send the 'compress' querystring
if (isset($_GET['compress'])) {
	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);
} else {
	header('Content-type: text/css; charset: UTF-8');
}
print(parseCss($css));


/*
* In the HTML file
*/
?>
<link rel="stylesheet" type="text/css" media="screen" href="css.php">
<!-- or if compressed -->
<link rel="stylesheet" type="text/css" media="screen" href="css.php?compress" />