I want to define some basic styles that I can combine. Let's say I have a stylesheet that contains the following lines:

.whitebackground  {background-color: #ffffff}
.borderblue       {border: solid 1px #0000aa}

I'm wondering if there is there a way to include these lines into a new line? Something like:

**div.main   {.whitebackground; .borderblue}**

The result must be the same as it would be with this line:

div.main  {background-color: #ffffff; border: solid 1px #0000aa}