diff --git a/docs/markmaker.py b/docs/markmaker.py
index bd5c0e5e..a6bd916b 100755
--- a/docs/markmaker.py
+++ b/docs/markmaker.py
@@ -76,7 +76,7 @@ def gentoc(titles, depth=0, chapter=0):
         return "  "*(depth-2) + "- [{}](#{})\n".format(titles, anchor(titles))
     if isinstance(titles, list):
         if depth==0:
-            sep = "\n\n<!-- auto-generated TOC -->\n---\n\n"
+            sep = "\n\n.debug[auto-generated TOC]\n---\n\n"
             head = ""
             tail = ""
         elif depth==1:
@@ -104,7 +104,7 @@ def processchapter(chapter, filename):
     if isinstance(chapter, str):
         if "\n" in chapter:
             titles = re.findall("^# (.*)", chapter, re.MULTILINE)
-            slidefooter = "<!-- {} -->".format(filename)
+            slidefooter = ".debug[{}]".format(filename)
             chapter = chapter.replace("\n---\n", "\n{}\n---\n".format(slidefooter))
             chapter += "\n" + slidefooter
             return (chapter, titles)
diff --git a/docs/workshop.css b/docs/workshop.css
index 8f993ba1..c7f61453 100644
--- a/docs/workshop.css
+++ b/docs/workshop.css
@@ -26,6 +26,18 @@ div.remark-slide-number {
   right: 6px;
 }
 
+.debug {
+  position: absolute;
+  left: 0px;
+  right: 0px;
+  bottom: 0px;
+  font-family: monospace;
+  color: white;
+}
+.debug:hover {
+  background-color: black;
+}
+
 body { font-family: 'Droid Serif'; }
 
 h1, h2, h3 {