Variables in Sass stylesheets are defined with dollar signs.

$zombie-skin:#BEDEAD;

 
 

...may be used in a style like so:

.zombie {
   color: #FF0000;
   background-color: $zombie-skin;
}

 
 

In the app I am immediately looking at there is a stylesheet with all of the common styles that is imported into the other stylesheets to allow them to use the reusable variables.