For some sites, safari 16.6 web inspector can't modify CSS

I was looking into making my banks website more ergonomic for myself and wanted to use developer tools - inspector to test some CSS modifications. But the inspector won't let me modify anything in CSS panel, there are no checkmarks, the values are not editable. Other websites work, just not the banks. (Read somewhere that it might be content blockers that are the culprit, but other websites work ok with the same blockers active). What gives? Can still modify the html. You don't actually have to log in to see it: Credit Agricole Thanks!