Regarding Revit 2019, the Grey on Grey Ribbon and Tabbed Menu is not very good. The majority of ALL books printed are black on white. Black on White generates maximum contrast. Grey on Grey might have looked cool ten years ago; but low contrast is not cool for productivity.
A forty year old person needs twice as much light as a twenty year old person. A sixty year old person needs three times as much light. With Grey on Grey; i.e. low low contrast, it literally takes an extra split second to find the icon on the menu bar.
Please Autodesk, create a user interface that creates high contrast in order to increase productivity and ease of use.