can i give a name to the css property

can i give a name to the css property

Here is an example:
This is the normal css:
h1{
background-color: #fafafa;
}
I would like to change this to the following:
h1{
background-color: default or any id name
}
Where can I give a javascript command to change this color code(i.e
#fafafa)? Where ever it is in the stylesheet to default or any id name. So
that I can use it in a color switcher to change the color for this code. I
don't want to use less because I have already gone way to far in my
project.