layouts: add spoiler shortcode

content/posts/hello-world.md

@@ -39,3 +39,11 @@ echo hello world | cut -d' ' -f 1
     \draw (0,0) circle (1in);
   \end{tikzpicture}
 {{% /tikz %}}
+
+### Spoilers
+
+{{% spoiler "Don't open me" %}}
+Test 2
+
+Test 3
+{{% /spoiler %}}

layouts/shortcodes/spoiler.html

@@ -0,0 +1,5 @@
+{{- $title := .Get "title" | default (.Get 0) -}}
+<details>
+    <summary>{{ $title }}</summary>
+    <p>{{.Inner}}</p>
+</details>