ability to override all CSS / HTML in dev-sever.

[zeroedin]

It would be handy to be able to override any of the HTML and/or CSS downstream for the dev server.

If you choose to provide your own layout/template or just the including the provided CSS or not.

[bennypowers]

Something like wtr's testRunnerHtml config callback is warranted here

[bennypowers]

take a look at RedHat-UX/red-hat-design-system#1887