Using a dynamic admin body class within WordPress to distinguish between light or dark admin interface.

README.md

WordPress Admin Interface

Full tutorial: http://hofmannsven.com/2013/laboratory/wordpress-admin-ui/

functions.php

<?php

add_filter( 'admin_body_class', 'admin_interface_version_body_class' );
function admin_interface_version_body_class( $classes ) {
  // check wp_version
  if ( version_compare( $GLOBALS['wp_version'], '3.8-alpha', '>' ) ) {
    $classes .= 'dark-admin-ui'; // new admin interface
  } else {
    $classes .= 'light-admin-ui'; // old admin interface
  }
    return $classes;
}

?>

plugin-options.php

<?php

add_filter( 'admin_body_class', 'admin_interface_version_body_class' );
function admin_interface_version_body_class( $classes ) {
  // check wp_version
  if ( version_compare( $GLOBALS['wp_version'], '3.8-alpha', '>' ) ) {
    $classes .= 'dark-admin-ui'; // new admin interface
  } else {
    // check admin_color
    if ( get_user_option( 'admin_color' ) === 'mp6' ) {
      $classes .= 'dark-admin-ui'; // updated old admin interface
    } else {
      $classes .= 'light-admin-ui'; // old admin interface
    }
  }
    return $classes;
}

?>

user-options.php

<?php

add_filter( 'admin_body_class', 'admin_interface_version_body_class' );
function admin_interface_version_body_class( $classes ) {
  // check wp_version
  if ( version_compare( $GLOBALS['wp_version'], '3.8-alpha', '>' ) ) {
    // check admin_color
    if ( get_user_option( 'admin_color' ) === 'light' ) {
      $classes .= 'light-admin-ui'; // custom new admin interface
    } else {
      $classes .= 'dark-admin-ui'; // new admin interface
    }
  } else {
    $classes .= 'light-admin-ui'; // old admin interface
  }
    return $classes;
}

?>