Refactoring of web design of Django web app

We are currently working on a web app that is based on this one here (https://github.com/fiduswriter/fiduswriter).

The web design looks as in old_writer.png (see the attachments). Currently, we want to refactor the web design of it and we started with it already (new_writer.png).
For instnace, the idea is to shift away from the colour green towards blue and a bit white and grey.
But also many other aspects have to be refactored
(see editor.png, my_account.png, overview.png, share_document.png, technical_support.png). For instance, the panels should align to the design of the login panel (new_writer.png).

Furthermore, the web app looks bad on a mobile device. Hence, in addition to the request from above you also should make everything look good on a mobile device.

Overall, there is quite some creativity allowed in terms of making things look cool. It is intended to have a frequent exchange such that the development works as desired.

The task will mostly cover Javascript, html, and css.