https://gitlab.synchro.net/main/sbbs/-/merge_requests/223#note_2885
Yes, multiple classes are allowed, and quite common with bootstrap. In this case 'alert' contains the generic styling that applies to all alerts (ie adding
a border with rounded corners), and then 'alert-*' contains styling related to colours (making the alert red in the case of danger)
--- SBBSecho 3.20-Linux
* Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)