A banner is essentially a Tour Step that displays full width at the top of a page. You can include the same components within a banner as in any other Step.
To create this, create an Announcement Tour and adjust its Step accordingly:
Set its Position to be 'Relative to Screen' and to show in the 'top-center- position
Set the Canvas width to 100%
Click on any buttons in the Step and choose 'Position = Center right' (this will make the buttons inline with your text)
You can configure any other components as normal. Some suggestions include:
Reduce the corner radius to 0 px
Note: This step will show as part of a Tour. If you'd like to create an independent banner, do not add any other Steps to the Tour.