removed unnecessary config

config/environment.default.js

@@ -158,6 +158,5 @@ module.exports = {
   },
   theme: {
     name: 'mantis',
-    cssClass: 'mantis',
   }
 };

src/config/theme.inferface.ts

@@ -2,5 +2,4 @@ import { Config } from './config.interface';
 
 export interface Theme extends Config {
   name: string;
-  cssClass: string;
 }