Once the final theme is agreed upon would Stack Exchange be open to submitting a PR to add the theme "officially" to the core project so smaller sites who enjoyed your theme could use it on their own sites, or would that not be something you'd want to do...?
We'd be happy to include it. (I'm the current maintainer of Highlight.js)
Anyone using Highlight.js could use the theme easily if they enjoyed it.
Perhaps you don't want to share your "brand" in that way?