Make all user profile pictures round I am trying to figure out how to apply a class to user profile pictures in Drupal 8 to make the pictures round. 

Since I am using Bootstrap 3 I can just apply image-round class in this case, but I am not sure how to add the class to the profile image. 

I tried adding a class with the Field Class module, but it didn't work.
In your file of your theme: "MYTHEME.theme"

Create hook_preprocess_image

/**
 * Implements hook_preprocess_image() to add classes to the search form.
 */
function MYTHEME_preprocess_image(&amp;$variables) {
  ksm ($variables);
    if ($variables['style_name'] == 'thumbnail') {
        $variables['attributes']['class'][] = 'image-rounded';
    }
}