Flash when using dark mode

[lukasjuhrich]

Currently, the dark mode is initiated by setting the data-bs-theme attribute on the html tag via some Javascript code.
Due to[1] latency in the execution of JS, this causes a flash.

Workaround

Hard-coding the dark theme as a default before the actual one is loaded would be a workaround, because a dark-then-bright flash is more bearable than a light-then-dark flash.

Better fix

To change bootstrap's behavior to use media queries instead of the data-bs-theme attribute, we need to set the sass attribute $color-mode-type: media-query;. That requires including a sass step in our webpack toolchain.

TODOs

• workaround: set data-bs-theme="dark", check whether the rest works correctly
• include sass in our webpack toolchain
• set the attribute
• remove the JS code (however, leave some code ensuring the local storage entries we used are deleted)

[1] unnecessarily high, but be that as it may