diff --git a/book/exercises/001.md b/book/exercises/001.md
index fa1d4c5..805faa6 100644
--- a/book/exercises/001.md
+++ b/book/exercises/001.md
@@ -35,4 +35,13 @@ Before moving on to the next exercise, make sure you understand the following:
 
 :::{exercise}
 <iframe src="https://tudelft.h5p.com/content/1292493455522610637/embed" aria-label="Testing more Teachbooks knowledge" width="1088" height="637" frameborder="0" allowfullscreen="allowfullscreen" allow="autoplay *; geolocation *; microphone *; camera *; midi *; encrypted-media *"></iframe><script src="https://tudelft.h5p.com/js/h5p-resizer.js" charset="UTF-8"></script>
+<style> 
+    @media (prefers-color-scheme: light) {
+        iframe[src*="tudelft.h5p.com"] {
+            filter: invert(1); 
+            background: transparent; 
+            mix-blend-mode: difference;
+        }
+    }
+</style>
 :::