Add live color preview to the styleeditor

[cls-design]

It would be nice to have some kind of live preview of the colours. The current situation is that a popup opens that darkens the background and you need several attempts to find a suitable colour.

It would be better if the colour selection was integrated in another way, for example as a fixed footer and the colour selection would also have a direct effect in the style preview.

For example:

Edit:

The idea is for the ‘new’ style editor, not for the current implementation which is more or less EOL 👀