diff --git a/theme/boost/templates/core/block.mustache b/theme/boost/templates/core/block.mustache
index 783fe9aebd2..11613736c9c 100644
--- a/theme/boost/templates/core/block.mustache
+++ b/theme/boost/templates/core/block.mustache
@@ -1,3 +1,18 @@
+{{!
+    @template theme_boost/block
+
+    Example context (json):
+    {
+        "id": "block0",
+        "showskiplink": true,
+        "type": "html",
+        "ariarole": "complementary",
+        "title": "Test block",
+        "blockinstanceid": 1,
+        "content": "<p>Hello block world!</p>"
+    }
+
+}}
 {{! Block Skip Link }}
 {{#showskiplink}}
   <a href="#sb-{{skipid}}" class="sr-only sr-only-focusable">{{#str}}skipa, access, {{title}}{{/str}}</a>
@@ -28,12 +43,12 @@
 
         {{! Block header }}
         {{#title}}
-            <h3 id="instance-{{blockinstanceid}}-header" class="card-title">{{{title}}}</h3>
+            <h3 id="instance-{{blockinstanceid}}-header" class="card-title header">{{{title}}}</h3>
         {{/title}}
 
-        <div class="card-text">
+        <div class="card-text content">
             {{{content}}}
-            {{{footer}}}
+            <div class="footer">{{{footer}}}</div>
             {{{annotation}}}
         </div>