Way before I implemented any themes, when the now classic theme was the only look available, I had a system that allowed authors to change the look of their own home pages on the site.
It had the default look and the blue look, and it also provided a kit to create a custom stylesheet for their own pages.
I hadn't touched this feature in a lonnnnng time, basically for the last 20 years or so.
I've finally made an update.
I added a couple of color themes, and updated the kit as well added allowing each author to simply upload their own stylesheet at will and use it. You don't need my help to put the stylesheet on the server anymore.
The new kit allows easy color scheme modification as the colors are listed as CSS variables now and it's just a matter of changing the colors to create new themes. The adventurous can edit the rest of the CSS rules for further customization if you wish.
If anybody creates an interesting look and would like to share it with other authors, you can send it to me and I'll add it to the system so that it's listed in the selector for everybody.
To access this customization system, go to the pen name management system and click the loop next to your pen name and then click 'Customize Home Page'.