What would be the proper size of the Masthead Background Image?

We suggest an image with the dimension of around 2000 x 400, which would work best.

Here is an example of 2000 x 390 by Stardekk:

https://res.cloudinary.com/apideck/image/upload/w_auto,f_auto/v1643122999/ecosystems/background-01-01_hz8fjb.png