gistfile1.php

public function main_css() {
  	$versionNum = '2.0';
		if(preg_match('/(?i)msie [1-8]/',$_SERVER['HTTP_USER_AGENT'])) {
		  	echo '<link rel="stylesheet" href="'.site_url( 'dr-content/themes/dr' ) . '/css/main.css?ver='.$versionNum.'" type="text/css" media="all" />';
		}
		else {
			wp_enqueue_style( 'dr-main-css', site_url( 'dr-content/themes/dr' ) . '/css/main.css', array(), $versionNum );
		}
	}
  
  add_action( 'wp_enqueue_scripts', array( $this, 'main_css' ) );