Customize login page for basic auth in dash-auth module


I have tried to explore all the code in dash-auth module (especially and but I could not figure out from where do we show the login dialog where user enters Username and Password.

I wish to modify the login experience with a simple good looking form with basic details like email, password, company etc.

Also I figured we are parsing Authorization header and extracting the encoded value for getting email+password. I also want to know where are we setting this field in Authorization header ?

Could anyone point me in right direction on how to do it ?