diff --git a/snikket_web/__init__.py b/snikket_web/__init__.py
index c5d01b4..5aeeda3 100644
--- a/snikket_web/__init__.py
+++ b/snikket_web/__init__.py
@@ -48,6 +48,7 @@ async def proc() -> typing.Dict[str, typing.Any]:
         "text_to_css": colour.text_to_css,
         "lang": infra.selected_locale(),
         "user_info": user_info,
+        "is_in_debug_mode": current_app.debug,
     }
 
 
diff --git a/snikket_web/scss/app.scss b/snikket_web/scss/app.scss
index c01ab7c..45e4c32 100644
--- a/snikket_web/scss/app.scss
+++ b/snikket_web/scss/app.scss
@@ -67,6 +67,10 @@ div#topbar {
 		font-size: $_top-h-size;
 		line-height: 1.5;
 
+		body.debug & {
+			color: red;
+		}
+
 		@media screen and (max-width: $small-screen-threshold) {
 			font-size: $_top-h-small-size;
 		}
diff --git a/snikket_web/templates/base.html b/snikket_web/templates/base.html
index d906bce..c42b42f 100644
--- a/snikket_web/templates/base.html
+++ b/snikket_web/templates/base.html
@@ -16,5 +16,5 @@
 		<meta name="msapplication-TileColor" content="#fbd308">
 		<meta name="theme-color" content="#fbd308">
 	</head>
-	<body{% if body_id | default(False) %} id="{{ body_id }}"{% endif %}{% if body_class | default(False) %} class="{{ body_class }}"{% endif %}{% if onload | default(False) %} onload="{{ onload }}"{% endif %}>{% block body %}{% endblock %}</body>
+	<body{% if body_id | default(False) %} id="{{ body_id }}"{% endif %} class="{% if is_in_debug_mode %}debug{% endif %}{% if body_class | default(False) %} {{ body_class }}{% endif %}"{% if onload | default(False) %} onload="{{ onload }}"{% endif %}>{% block body %}{% endblock %}</body>
 </html>