themeing harmony todo-list

Here's things I didn't bother themeing/harmonizing when i quickly hacked this up, and ostensibly should get a proper pass (fine if the answer is "what we have now is fine", should still validate that):

* [ ] main content
* [ ] code-blocks / inline-code
* [ ] tables
* [ ] lists
* [ ] --fg (main text color)
* [ ] misc padding/spacing
* [ ] chrome
* [ ] search bar
* [ ] theme selector menu
* [ ] header/footer/sidebar bg-color/separator

No files, tests, or entry points are named in the issue. Review the current theme implementation and compare the listed main-content and chrome elements across the available themes; done means each item has been validated and either harmonized or explicitly confirmed as acceptable.

Written by the indexing model from the issue text.