Display Banner in Dashboards when database is down or during maintanence time

Hi Team,

The requirement in general is to find a way to place a upper banner on all the dashboards with a Maintenance legend or data error being revised or something like that. So whenever there is a maintenance or issue in db no need for the code promotion automatically it should be updated in the dashboard.

Basically, we need to display a message whenever there is downtime/database is down so users will get a notification once they try to open the Looker Dashboard and when they are unable to access the Dashboard.

Please let me know your inputs.