The graph can accept color values in the same format as colors are defined within an HTML page. ie. in the range and format from "#000000" to "#FFFFFF".

gridbgcolor: #FFFFFF

This is a Red,Green,Blue color model where each component is defined by a 2 byte (character) Hexadecimal number. Some common values are,

The graph will also recognize all of the following color names and as such you can use these names as the value of any Color parameter.

gridbgcolor: light blue