How do you clean glass shower doors and enclosures resting on marble flooring?

I have a marble bath with all glass enclosures. Now with the soap scum and water spots, the normal soap and scrubbing action does not work anymore.
However most of the detergents say do not use on Marble?!! So how can I clean the glass without getting detergent on the marble? Or rather, is there a product out there that is safe to drip on marble? Btw, I have crema marfil, which is considered pretty porous and is beige in color.