Set meta prop "theme-color"
The new Safari on macOS decorates the tab bar with the color from <meta name="theme-color" content="#375f7E">

Check if we can use the brand color from the currently loaded theme there.
cc @michaelstingl
Perhaps not working, see https://css-tricks.com/meta-theme-color-and-trickery/#custom-properties
@kulmann can you assign this issue to me. I want to work on this issue.
Can probably be added here: https://github.com/owncloud/web/blob/8723750b07ce49b04a9d0a3c46ebc064eedbe2f2/packages/web-runtime/src/composables/head/useHead.ts
Can probably be added here: https://github.com/owncloud/web/blob/8723750b07ce49b04a9d0a3c46ebc064eedbe2f2/packages/web-runtime/src/composables/head/useHead.ts
I was just about to post the very same link 😆 Thank you @dschmidt !
@kulmann I have added the meta prop "theme-color"