Sorry for the trouble. We've realized that there is no way to set the Super Admin group to 'Denied'. It works for all other groups.
To completely disable, please edit the /components/com_jfbconnect/libraries/toolbar.php file. Around line 17, you'll see:
public function onAfterDispatch()
{
if (JFactory::getUser()->authorise('jfbconnect.channels.post', 'com_jfbconnect'))
{
Update that by changing the if statement to 'false' like below:
public function onAfterDispatch()
{
if (false)
{
Do the same for the onAfterReturn function at line 44.
That will disable the toolbar altogether.
As for the CSS issues, the problem is because we're loading the jQuery UI CSS file for the Toolbar. We've already stripped out additional code that we aren't using in that file, but will look to see if we can namespace things further to ensure it only affects JFBConnect features.
Thanks,
Alex