I took some time to adapt @agiletortoise’s “Vivid Dark+” theme to my personal needs and taste.
The background is changed to true black which is great on OLED displays.
To easily distinguish between different workspaces I use in Drafts I created several versions with different highlight colors. This enables me to use the same theme just differentiated by highlight colors for visual separation 
You can view and download the different themes from the Drafts directory:
Let me know if you would like to have other highlight colors or simply use the Online Theme Builder of Drafts to modify it to your needs: Theme Builder - Drafts Tools