Hello
All buttons in Commerce » Orders » Processing
are black
with white background and white text on mouse over.
Any idea ?
Can you check your custom template directory for an admin directory? That looks a lot like you’ve copied all the templates (rather than only the ones you’ve customised) and the admin markup no longer matches the CSS.
As a general rule, only keep customised templates in your template directory - do not duplicate the entire templates directory, and remove any template you did not change so that can properly fall back to the default. And never include the admin templates unless instructed by support as we do not consider changes to the admin markup to be breaking changes and may incorporate such changes in patch releases.