diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000000000000000000000000000000000..822f448577fd54bc1a81827516065bc405f49fb7
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "css/tufte-css"]
+	path = css/tufte-css
+	url = https://github.com/edwardtufte/tufte-css.git
diff --git a/css/tufte-css b/css/tufte-css
new file mode 160000
index 0000000000000000000000000000000000000000..e225f3a0e5f8f42a1d28416c1c85962411711907
--- /dev/null
+++ b/css/tufte-css
@@ -0,0 +1 @@
+Subproject commit e225f3a0e5f8f42a1d28416c1c85962411711907