I'm looking for the best way to inject CSS into WordPress' Admin CP.

Currently, I'm using the admin_head action hook and in this hook, I'm using dirname( __FILE__ ) to retrieve the directory for the stylesheets. However, dirname() does retrieve the server's path. Is this the recommended way or is there some sort of WordPress function to get a URI path rather than a directory path?

    public function admin_head()
        // Let's include the Control Panel CSS
        $url = dirname( __FILE__ ) . '/css/cpanel.css';
        $ie = dirname( __FILE__ ) . '/css/cpanel-ie.css';

        // Inject our cPanel styelsheet and add a conditionaly for Internet Explorer
        //      (fixes bugs on my home browser)
        $head = <<<HEAD
    <link rel="stylesheet" href="{$url}" type="text/css" media="screen" />
    <!--[if IE]>
        <link rel="stylesheet" type="text/css" href="{$ie}" media="screen" />

        echo $head; 

        foreach( self::$classes as $class => $obj )
            if ( method_exists( $obj, 'admin_head' ) )


3 Answers 3


See plugins_url(). It's perfect and engineered to link to files in plugin folders.

PS also wp_enqueue_style() might make sense in the mix.

  • Hmmm. wp_enqueue_style: can that be used to inject css based upon browser? Or would the general idea I have (only with plugins_url) be the best way to do that?
    – Zack
    Feb 25, 2011 at 21:15
  • 1
    @Zack I vaguely remember there is $is_IE global var, never used that myself. See vars.php.
    – Rarst
    Feb 25, 2011 at 21:21

There's another way to add conditional comments, using WP's API:

     get_template_directory_uri() . '/css/cpanel-ie.css'

global $wp_styles;
$wp_styles->add_data( 'my-ie-style', 'conditional', 'IE' );


  • 1
    Wow! Never knew this. For those who interested here is chunk of code that handles this in source.
    – Rarst
    Feb 25, 2011 at 21:45
  • +1. Great example of the kind of hidden API functions that make me keep loving WordPress! Feb 25, 2011 at 22:17
  • I'm drawn to this snippet. I really like it. I'll look into it further after I've tested @mfields 's answer.
    – Zack
    Feb 25, 2011 at 22:19
  • That is definitely neat! Have really had no need to dig into the Dependencies class before. @filosofo While I agree that this seems to be a more direct approach, I try to avoid touching global objects as much as possible in extensions and use hooks wherever possible.
    – mfields
    Feb 25, 2011 at 22:40

I originally didn't think that this was possible, but then I did some digging and came up with the following solution which works for me on WordPress 3.1. The tricky part was getting the conditional tags for IE in there. There's a filter for it!

Plugin Name: My Plugin
class My_Plugin {
    function My_Plugin() {
        add_action( 'wp_print_styles', array( &$this, 'css_public' ) );
        add_filter( 'style_loader_tag', array( &$this, 'ie_conditional_comments' ), 10, 2 );
    function css_public() {
        wp_enqueue_style( 'my-plugin', plugins_url( '/my.css', __FILE__ ), array(), '1.0' );
        wp_enqueue_style( 'my-plugin-ie', plugins_url( '/my-ie.css', __FILE__ ), array( 'my-plugin' ), '1.0' );
    function ie_conditional_comments( $tag, $handle ) {
        if ( 'my-plugin-ie' == $handle ) {
            $tag = '<!--[if IE]>' . $tag . '<![endif]-->';
        return $tag;
$my_plugin = new My_Plugin();

Best wishes, -Mike

  • 1
    Nice snippet! But for admin it would probably be easier to (not) queue depending on global var for IE, since there is no static caching scenario to worry about.
    – Rarst
    Feb 25, 2011 at 21:37
  • This looks like something I need, I'm playing with it right now and will come back to mark an answer as 'The Answer' ;)
    – Zack
    Feb 25, 2011 at 22:18

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