OH3 widget

Newbie question:
Is it posible to change the background color of a widget on the Overview page?
Or the colums or rows?

Yes. Go to the Item’s page, click on “add metadata” and for that widget click on “Default cell widget” (or something like that. You can fully customize the widget from there. That is for the Locations, Equipment, and Properties tabs.

For the main page, you have full control over all the widgets that get placed on it. However, if you use “Add widgets from model” (or something like that), it will use the default widgets defined in the metadata at the time the widget was added (if you change the metadata later it will not update the Page widget).