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. 
 
     
     
     
    