In the moment only one style class is rendered tobago-<rendererName>-error.
It would be better, when the style class depends on the severity level of the corresponding component, especially for labels.
To look forward in the future of the naming schema, it might be a good idea to use "markup" to implement this feature. Then we will have names like this:
For backward compatibility the old name will not be deleted in the Tobago 1.0.x branch.