For me it seems to have fixed it by turning "block trackers" off, so that it is disabled. The setting is just underneath where you turn the addblocker on or off.
As a developer of AreWeGood.fit web site I'd like to recommend, that Opera respects the CSS colors, if there is a corresponding color theme in either dark or light @media themes. Otherwise there is no way for us to force the colors, other than embedding text in the background images. Not a great alternative.