Unlike some other Bootstrap components like Buttons, the Alerts do not come with a
primary styling, because they are meant to alert the user in a specific way.
<div class="alert alert-success" role="alert">
Some action was completed successfully
<div class="alert alert-info" role="alert">
Here is some information. Just FYI.
<div class="alert alert-warning" role="alert">
Careful! You're about to do something dangerous.
<div class="alert alert-danger" role="alert">
An error (or something dangerous) happened!