title: is there a way to change the color of the outside area in a mddialog?
body: <p>Hello I am trying to change the color of a simple md dialog outside area from a dark transparent color to a different one it could either be darker or brighter, is this possible? Thank you for your help!</p>
  
  <p>code from <a href="https://material.angularjs.org/latest/demo/dialog" rel="nofollow noreferrer">https://material.angularjs.org/latest/demo/dialog</a>:</p>
  
  <pre><code>$scope.showAlert = function(ev) {
      // Appending dialog to document.body to cover sidenav in docs app
      // Modal dialogs should fully cover application
      // to prevent interaction outside of dialog
      $mdDialog.show(
        $mdDialog.alert()
          .parent(angular.element(document.querySelector('#popupContainer')))
          .clickOutsideToClose(true)
          .title('This is an alert title')
          .textContent('You can specify some description text in here.')
          .ariaLabel('Alert Dialog Demo')
          .ok('Got it!')
          .targetEvent(ev)
      );
    };
  </code></pre>