Fixed selectors getting overwritten

Author: samuelmaddock

lib/loader.js

@@ -10,12 +10,12 @@ const extractThemeRulesPlugin = postCssPlugins.extractThemeRulesPlugin;
 const removeCssModuleExports = postCssPlugins.removeCssModuleExports;
 
 const stringifyRuleMap = (ruleMap) => {
-    return Object.keys(ruleMap).reduce((acc, selector) => {
+    return Object.keys(ruleMap).map(selector => {
         const declsMap = ruleMap[selector];
         const decls = Object.keys(declsMap).map(prop => `${prop}: ${declsMap[prop]};`);
 
         return `${selector} {\n\t${decls.join('\n\t')}\n}`;
-    }, '');
+    }).join('\n');
 };
 
 // copied from css-loader/lib/getLocalIdent.js