Bibliotecas necessárias: LessPHP, CSSTidy, Minify.
define('DEBUG_MODE', true);
$lessFile = './less/style.less';
$lessCache = './cache/style.css.cached';
$lessCached = (file_exists($lessCache)) ? unserialize(file_get_contents($lessCache)) : $lessFile;
$lessParsed = lessc::cexecute($lessCached);
if(!is_array($lessCached) || $lessParsed['updated'] > $lessCached['updated']) {
file_put_contents($lessCache, serialize($lessParsed));
}
$cssCode = $lessParsed['compiled'];
$css = new csstidy();
$css->set_cfg('preserve_css', false);
$css->set_cfg('optimise_shorthands', 3);
$css->set_cfg('merge_selectors', 1);
$css->set_cfg('discard_invalid_properties', 1);
$css->parse($cssCode);
$cssCode = $css->print->plain();
header('Content-type: text/css');
if(DEBUG_MODE) {
header("Cache-Control: no-cache");
header("Pragma: no-cache");
echo $cssCode;
} else {
echo CssMin::minify($cssCode);
}