diff --git a/main.go b/main.go
index a41424c..ad6848c 100755
--- a/main.go
+++ b/main.go
@@ -180,6 +180,7 @@ func withMD(dir string, enabled bool, mdCss, mdClass string, foo http.HandlerFun
 			}
 			fmt.Fprintln(w, mdCss)
 			fmt.Fprintf(w, "<div class=%q>", mdClass)
+			s = strings.ReplaceAll(s, "<nav>", `<nav class="toc">`)
 			fmt.Fprintln(w, s)
 			fmt.Fprintf(w, "</div>")
 		} else {