diff --git a/src/courseware/course/sequence/Unit/hooks/useModalIFrameData.js b/src/courseware/course/sequence/Unit/hooks/useModalIFrameData.js
index ccb0fb59e0..513b0b7636 100644
--- a/src/courseware/course/sequence/Unit/hooks/useModalIFrameData.js
+++ b/src/courseware/course/sequence/Unit/hooks/useModalIFrameData.js
@@ -9,7 +9,7 @@ export const stateKeys = StrictDict({
   options: 'options',
 });
 
-export const DEFAULT_HEIGHT = '100vh';
+export const DEFAULT_HEIGHT = '100%';
 
 const useModalIFrameData = () => {
   const [isOpen, setIsOpen] = useKeyedState(stateKeys.isOpen, false);