diff --git a/subjects/action-reaction/README.md b/subjects/action-reaction/README.md
index 4f2c2ed3e..aa9cd1d6b 100644
--- a/subjects/action-reaction/README.md
+++ b/subjects/action-reaction/README.md
@@ -7,7 +7,7 @@ Let's put a button on the top right corner of the page, that will toggle (close
Add it in the HTML structure:
```
-
+
```
Add the style in the CSS file: