The .ui-growl-item-container.ui-state-highlight.ui-growl-message-... (success, error, etc) are not defined in the bootstrap theme css.
Agree, be good if this is fixed. Also note this shows up on the PrimeNG Demo site when you select the bootstrap theme.
Currently we are working on a brand new bootstrap theme according to bootstrap 4.So all of the problems about growl will be solved after that we are trying to accomplish this to the 1.0.2.
Sounds great, thanks for the update!