You probably want transparent as none is not a valid background-color value.

The CSS 2.1 spec states the following for the background-color property:

Value: <color> | transparent | inherit

<color> can be either a keyword or a numerical representation of a colour. Valid color keywords are:

aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive,
orange, purple, red, silver, teal, white, and yellow

transparent and inherit are valid keywords in their own right, but none is not.