Revert #3475

Was an accidental merge.

docs/classDiagram.md

@@ -660,14 +660,27 @@ It is also possible to attach a class to a list of nodes in one statement:
 
 A shorter form of adding a class is to attach the classname to the node using the `:::` operator:
 
-```mmd
+```mermaid-example
+classDiagram
+    class Animal:::cssClass
+```
+
+```mermaid
 classDiagram
     class Animal:::cssClass
 ```
 
 Or:
 
-```mmd
+```mermaid-example
+classDiagram
+    class Animal:::cssClass {
+        -int sizeInFeet
+        -canEat()
+    }
+```
+
+```mermaid
 classDiagram
     class Animal:::cssClass {
         -int sizeInFeet