diff --git a/local/frame/frame.html b/local/frame/frame.html
index 3694e6d..ed9f0f7 100644
--- a/local/frame/frame.html
+++ b/local/frame/frame.html
@@ -25,6 +25,8 @@
         <div id="frame">
             <div class="rmg-window__header">Frame Header</div>
             <div class="rmg-window__header rmg-window__app-clip-header">App Clip Header</div>
+            <div class="rm-window__header">Frame Header (Mantine)</div>
+            <div class="rm-window__header rm-window__app-clip-header">App Clip Header (Mantine)</div>
         </div>
 
         <script type="module" src="frame.js"></script>
diff --git a/src/service/frame.ts b/src/service/frame.ts
index 99290e9..683b83f 100644
--- a/src/service/frame.ts
+++ b/src/service/frame.ts
@@ -26,7 +26,8 @@ const injectUITools = () => {
 
     // define indent style
     const indentHeader = document.createElement('style');
-    indentHeader.textContent = '.rmg-window__header:not(.rmg-window__app-clip-header){margin-left: 40px;}';
+    indentHeader.textContent =
+        '.rmg-window__header:not(.rmg-window__app-clip-header),.rm-window__header:not(.rm-window__app-clip-header){margin-left: 40px;}';
 
     // first render
     if (!isStandaloneWindow() && !isRMTMenuShown()) {