diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9822bb2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+diag.html
+diag.txt
diff --git a/Makefile b/Makefile
index d6b5ff6..59d6e02 100644
--- a/Makefile
+++ b/Makefile
@@ -2,5 +2,8 @@
 diag.txt: diag_inp.txt box.sh
 	graph-easy < $< | sh box.sh > $@
 
+diag.html: diag.txt
+	(cat $<; echo; echo '<!-- Markdeep: --><style class="fallback">body{visibility:hidden;white-space:pre;font-family:monospace}</style><script src="markdeep.min.js" charset="utf-8"></script><script src="https://casual-effects.com/markdeep/latest/markdeep.min.js" charset="utf-8"></script><script>window.alreadyProcessedMarkdeep||(document.body.style.visibility="visible")</script>') > $@
+
 diagtest:
 	ls box.sh diag_inp.txt Makefile | entr sh -c 'make diag.txt && cat diag.txt'