added different background colors in header

[akankshat05]

Fixes 1384.
Added different background header colors (From the theme file) for the development and staging environments.

Staging :

Local :

[gabrielBusta]

Once you add the environment global I can land this and try it out on our staging instance

[bhearsum]

@akankshat05 - is this ready for another look? (Please make sure to press the re-request review button next to @gabrielBusta's name if so - otherwise we can't be sure.)