php压缩CSS

php压缩CSS后调用，html代码里面调用的是style.php文件

<?php
    ob_start ("ob_gzhandler");
    header("Content-type: text/css; charset: UTF-8");
    header("Cache-Control: must-revalidate");
    $offset = 60 * 60 ;
    $ExpStr = "Expires: " .
    gmdate("D, d M Y H:i:s",
    time() + $offset) . " GMT";
    header($ExpStr);
?>
body { color: red; }

html这样调用

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