diff --git a/framework/core/js/src/common/utils/isDark.ts b/framework/core/js/src/common/utils/isDark.ts
index fd0ea4b61f..a6b92d8447 100644
--- a/framework/core/js/src/common/utils/isDark.ts
+++ b/framework/core/js/src/common/utils/isDark.ts
@@ -17,7 +17,10 @@ export default function isDark(hexcolor: string | null): boolean {
   let hexnumbers = hexcolor.replace('#', '');
 
   if (hexnumbers.length === 3) {
-    hexnumbers = hexnumbers.split('').map(char => char.repeat(2)).join('');
+    hexnumbers = hexnumbers
+      .split('')
+      .map((char) => char.repeat(2))
+      .join('');
   }
 
   const r = parseInt(hexnumbers.slice(0, 2), 16);
diff --git a/framework/core/js/src/forum/components/IndexSidebar.tsx b/framework/core/js/src/forum/components/IndexSidebar.tsx
index b7fe99d88f..4595f0486a 100644
--- a/framework/core/js/src/forum/components/IndexSidebar.tsx
+++ b/framework/core/js/src/forum/components/IndexSidebar.tsx
@@ -7,13 +7,14 @@ import Button from '../../common/components/Button';
 import SelectDropdown from '../../common/components/SelectDropdown';
 import listItems from '../../common/helpers/listItems';
 import LinkButton from '../../common/components/LinkButton';
+import classList from '../../common/utils/classList';
 
 export interface IndexSidebarAttrs extends ComponentAttrs {}
 
 export default class IndexSidebar<CustomAttrs extends IndexSidebarAttrs = IndexSidebarAttrs> extends Component<CustomAttrs> {
   view(vnode: Mithril.Vnode<CustomAttrs, this>): Mithril.Children {
     return (
-      <nav className="IndexPage-nav sideNav">
+      <nav className={classList('IndexPage-nav sideNav', this.attrs.className)}>
         <ul>{listItems(this.items().toArray())}</ul>
       </nav>
     );