Step 1

Create a new file called .htaccess in the same directory your stylesheet is in. Open your newly created .htaccess file and add the following lines:

<Files style.css>
SetHandler application/x-httpd-php
</Files>

(Replace style.css with the filename of your stylesheet)

Step 2

Open up your stylesheet and add the following to the top of your stylesheet:

<?php
header('Content-type: text/css');
function compress($buffer) {
$buffer = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $buffer);
$buffer = str_replace(array("\r\n", "\r", "\n", "\t", ' ', ' ', ' '), '', $buffer);
return $buffer;
}
ob_start("compress");
?>

Now add this to the bottom of your stylesheet:

<?php ob_end_flush(); ?>

Step 3

That's all there is to it! Now open up your browser and point it to your stylesheet. All the comments and spacing should be removed, and it should look something like this.