615dcd5f89
Make use of the [`color-scheme` meta tag][0] to style buttons and other widgets to match the selected color scheme. When the scheme is toggled, the `content` of the tag is set to "light" or "dark" to tell the user agent how to theme input elements, which should match the colors of the rest of the app. [0]: https://html.spec.whatwg.org/multipage/semantics.html#meta-color-scheme
