PLT-6614 - Mentions badge styling and dropdown icon style (#6426)

* Mentions badge styling and dropdown icon style

* PLT-6134 - Fixing emoji picker border in RHS

webapp/components/team_sidebar/components/team_button.jsx

@@ -40,7 +40,7 @@ export default class TeamButton extends React.Component {
 
             if (this.props.mentions) {
                 badge = (
-                    <span className='badge pull-right small'>{this.props.mentions}</span>
+                    <span className='mention-badge pull-right small'>{this.props.mentions}</span>
                 );
             }
         }