I just started with sass and installed prepros. I tried to compile an .scss file and got an error:
Syntax error: Invalid CSS after \" color: \": expected exp
It looks like your syntax is wrong. In Sass, @ is for things like imports, media directives, partials (includes) and extends.
@
If you want to define a specific value for blue, and then reuse it, then the syntax is something like this:
$blue: #3333FF; a { font-weight: bold; color: $blue; }