Switching an app to high contrast?

Folks, is there a way to switch Lumo-based app to a high contrast, Particularly, I’d like to have have black font on white. Fields, V/H layouts etc. Thanks!

Looks like that is a missing feature: WCAG 2.1 level AAA conformant High Contrast variant for Lumo theme · Issue #5608 · vaadin/web-components · GitHub

I’m not really concerned about accessibility legislations, these things take time to form. My question is in the now: how do I switch all the BG to white, and all text to black?

It should be straightforward by just setting the values of the CSS custom properties

E.g. --lumo-base-color is the variable for the background and --lumo-body-text-color is color used for most of the texts. There are also other text colors, like primary etc.

The full list is here: Color | Lumo Style Properties | Lumo | Styling | Vaadin Docs