I've taken the Holker Homes theme and started to modify it.
It is very close to how I want it to be, but I cannot fathom how to turn the semi-opaque black background of the mobile menu to the grey I've used for the menu in the header.
No matter what I try, the code for background-color will not change from 14, 14, 14, .9 to 230, 230, 230, 1
(Container #menu.menu-wrapper.mobile-menu)
i'm sure there must be something I'm missing or not doing correctly, but I simply can't figure it out. Can someone please point me to how to resolve this

Projest file is attached.
Note: I can open the main.css file in Coda and edit the background-color to the correct value, but I'd really like to know how to change it in SD too.
Thanks in advance.
Charles