[css-anchor-position-1] How to style anchor based on anchored's chosen fallback?

[lukewarlow]

I have the following select element:

I can easily style it such that the picker has a flat top edge, and that the select has a flat bottom edge. BUT if the select then renders such that the picker uses a fallback position where it's above the select, these styles now long weird.

I believe that using the @container anchored(fallback: ...) we can change the styles of the picker (or a wrapper child within the picker I guess). I don't think there's any such mechanism to style the select itself based on the pickers location though?

I realise this might just not be possible with CSS due to cycles but thought I'd raise the use case.