diff --git a/docs/index-test.md b/docs/index-test.md
index b0d4dff..83fbe67 100644
--- a/docs/index-test.md
+++ b/docs/index-test.md
@@ -310,7 +310,17 @@ graph TD;
     C-->D;
 ```
 
+### Collapsed Section
 
-```
-The final element.
-```
+The following uses the [`<details>`](https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/organizing-information-with-collapsed-sections) tag to create a collapsed section.
+
+<details markdown="block">
+<summary>Shopping list (click me!)</summary>
+
+This is content inside a `<details>` dropdown.
+
+- [ ] Apples
+- [ ] Oranges
+- [ ] Milk
+
+</details>