Provide contextual feedback messages for typical user actions with the handful of available and flexible alert messages.
Wrap any text and an optional dismiss button in .alert and one of the four contextual classes (e.g., .alert-success) for basic alert messages.
Alerts don't have default classes, only base and modifier classes. A default gray alert doesn't make too much sense, so you're required to specify a type via contextual class. Choose from success, info, warning, or danger.