Meta topic: https://meta.discourse.org/t/meta-theme-color-is-not-respecting-current-color-scheme/239815/7?u=osama.
This commit renders an additional `theme-color` `<meta>` tag for the dark scheme if the current user/request has a scheme selected for dark mode. We currently only render one `theme-color` tag which is always based on the user's selected scheme for light mode, but if the user also selects a scheme for dark mode and uses a device that's configured to use/prefer dark mode, the Discourse UI will be in dark mode, but any parts of the browser/OS UI that's colored based on the `theme-color` tag, would use a color from the user's selected light scheme and look inconsistent with the Discourse UI because the `theme-color` tag is based on the user's selected light scheme.
The additional `theme-color` tag has `media="(prefers-color-scheme: dark)"` and is based on the user's selected dark scheme which means any browser UI that's colored based on `theme-color` tags should be able to pick the right tag based on the user's preference for light/dark mode.
Follow up to: #17619
Context: https://meta.discourse.org/t/introducing-discourse-splash-a-visual-preloader-displayed-while-site-assets-load/232003/17
We previously relied on the user's browser when deciding when to show the splash in light/dark mode. This worked well but can fail if the user manually selects a theme with a default "dark" scheme.
This PR will now factor that in. If the user selects a theme with a default dark scheme, use that. If a user selects a theme with a "light" default scheme and also picks a secondary "dark" scheme, use the media detection we had before.
This PR also removes the dark mode theme-color that was added in the previous PR. That will now go in a separate PR
Context: https://meta.discourse.org/t/introducing-discourse-splash-a-visual-preloader-displayed-while-site-assets-load/232003/17
We currently set the theme secondary color as the background for the splash, and this works and respects light/dark modes.
The issue is that we set it on the #d-splash div. That div doesn't have a specified height and only gets its height when the splash image loads.
This can cause a flicker effect where the <HTML> background shows for a fraction of a second while the splash image loads.
This PR sets the theme color on the <HTML> tag to alleviate this. This allows us to set the theme color a little bit sooner and should hopefully prevent the flicker effect from happening.
This PR also adds the theme-color <meta> tag for dark mode. Browsers that don't support multiple theme-color tags will ignore the second tag and fall back to the first one.
DEV: Replace instances of Discourse.base_uri with Discourse.base_path
This is clearer because the base_uri is actually just a path prefix. This continues the work started in 555f467.
Minor fixes to add Rails 6 support to Discourse, we now will boot
with RAILS_MASTER=1, all specs pass
Only one tiny deprecation left
Largest change was the way ActiveModel:Errors changed interface a
bit but there is a simple backwards compat way of working it
on iOS 10 behavior of zoom restriction has changed.
This does not disable zooming on iOS 10 but it DOES stop it from randomly
zooming when you are composing
The opensearch.xml results in a "site search engine" being added to
Chrome, while the sitelinks search tag results in "Search this website"
being added to Google Search.
