Merge pull request #2 from longlho/patch-1

Prefix hashes with underscores based on CSS spec

Author: mightyaleksey

index.js

@@ -41,6 +41,6 @@ module.exports = function createGenerator(pattern, options) {
     var genericName = interpolateName(loaderContext, name, loaderOptions);
     return genericName
       .replace(new RegExp('[^a-zA-Z0-9\\-_\u00A0-\uFFFF]', 'g'), '-')
-      .replace(/^([^a-zA-Z_])/, '_$1');
+      .replace(/^((-?[0-9])|--)/, "_$1");
   };
 };