diff --git a/config/environment.default.js b/config/environment.default.js
index 5aac63fd3d..025939c9db 100644
--- a/config/environment.default.js
+++ b/config/environment.default.js
@@ -158,6 +158,5 @@ module.exports = {
   },
   theme: {
     name: 'mantis',
-    cssClass: 'mantis',
   }
 };
diff --git a/src/config/theme.inferface.ts b/src/config/theme.inferface.ts
index dc5a870f6e..d0cf1d77d8 100644
--- a/src/config/theme.inferface.ts
+++ b/src/config/theme.inferface.ts
@@ -2,5 +2,4 @@ import { Config } from './config.interface';
 
 export interface Theme extends Config {
   name: string;
-  cssClass: string;
 }