Adapt to Syntax themes?

Should this UI theme also adapt to syntax themes by using the syntax variables as a base? Like the One themes and others do it.

**Pro**: It would look much better because the current dark grey rarely matches any syntax's theme background color.

**Con**: On the other hand, the purpose of this theme is to make it as easy as possible for beginners to get started. Without any fancy stuff. So not sure.

The issue proposes adapting the UI theme to syntax theme variables, but it names no files, tests, or entry points. First resolve whether matching syntax backgrounds outweighs the template's goal of simple beginner setup; the issue does not define acceptance criteria for either outcome.

Written by the indexing model from the issue text.