Proxima has made a number of tiles in various colours which are intended to match one of the original styles:
(https://i.imgur.com/dYGO92o.png)
Amiga blue, which I'd suggest be added to all of them
(https://i.imgur.com/eVnUTXr.png)
A slightly cooler shade of blue, intended for use with orig_crystal
(https://i.imgur.com/ebSA8pG.png)
Brown, intended for use with orig_dirt, orig_pillar
(https://i.imgur.com/weDKf5W.png)
Indigo, intended for use with orig_marble
(https://i.imgur.com/sc4lEjd.png)
Olive, intended for use with orig_pillar, ohno_rock
(https://i.imgur.com/yGbUS4t.png)
Purple, intended for use with orig_marble, ohno_bubble, ohno_rock
(https://i.imgur.com/KOxer07.png)
Red, intended for use with orig_fire, ohno_brick
I'd like to suggest that we go ahead and add these to the original styles as background images. It's KB of difference in file size for easy access to these style-enhancing background colours. Note that adding these will not change the theme background colour, it will simply make the background available alongside each of the suggested styles in the Editor.
If there are no objections, this will go ahead at the end of March.