diff --git a/build.py b/build.py
index aa7690c..5c4a630 100755
--- a/build.py
+++ b/build.py
@@ -309,9 +309,7 @@ border: none;
 height: 4em;
 }}
 
-/*
-
-* {{
+.debug {{
 border-color: rgb(255,0,255);
 border-style: solid;
 border-width: 1px;
@@ -332,6 +330,12 @@ function check(tab) {{
     }}
 }}
 
+function debug() {{
+    for (element of document.getElementsByTagName('*')) {{
+        element.classList.toggle('debug')
+    }}
+}}
+
 function push(tab) {{
     window.history.pushState(null, null, `?tab=${{tab}}`)
 }}
@@ -838,7 +842,10 @@ tabs = {
 ''',
 #⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅
     'style': f'''\
-<input type="checkbox" id="dark" onclick="swap()">Dark</input>
+<ul>
+<li><input type="checkbox" id="dark" onclick="swap()">Dark</input></li>
+<li><input type="checkbox" id="debug" onclick="debug()">Debug</input></li>
+</ul>
 ''',
 #⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅
     'tasks': f'''\