Code i added ([a-zA-Z0-9\_\-]+) but not work i wan't to include all css files is there is any other way to add??

My code file css.php

header("Content-type: text/css");
$css = array(
     '([a-zA-Z0-9\\_\\-]+).css',
);

foreach ($css as $css_file) {
    $css_get = file_get_contents($css_file);
    echo $css_get;
    }

call.php

<link href="css.php" rel="stylesheet" type="text/css" />

i wan't to rewrite css.php to css.css so public can see css.css instead of css.php. how can i do that using php script?