Change top Menu button font color and Icon in Mobile

Hi, I have some webpages with light background and I've used additional CSS to change the top menu color for desktop mode. In mobile mode, I don't have an issue with the drop down part, since it has its own background but with the "Menu" button of the widget. I can change its background color but I cannot seem to be able to change the font color to black. Just for the "Menu" notation and the list icon next to it. Can you give me a hand? Thank you