chore: ADR for theming

[Sander3003]

Add a list of viriables: what to theme (colors + text + fonts) Error messages should be consistent (this is possible)

[Sander3003]

Main motivation to do so: the action pane is currently not themeable.

[pascalwilbrink]

List of (current) css variables:

--oscd-color-primary
--oscd-color-secondary

--oscd-theme-primary: var(--oscd-color-primary)
--oscd-theme-background

--oscd-theme-surface
--oscd-theme-on-primary
--oscd-theme-on-secondary
--oscd-theme-on-background
--oscd-theme-on-surface

--oscd-theme-text-primary
--oscd-theme-text-secondary
--oscd-theme-text-icon

--oscd-theme-state-error
--oscd-theme-state-warning
--oscd-theme-state-info
--oscd-theme-state-success

--oscd-icon-font

[Sander3003]

Any idea where to store these css variables?

[pascalwilbrink]

Any idea where to store these css variables?

We need a Developers documentation where we can store this