diff --git a/.gitmodules b/.gitmodules
index d9ae2925..6192a69b 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "breathe"]
 	path = breathe
 	url = git://github.com/vitaut/breathe.git
+[submodule "doc/sphinx-bootstrap-theme"]
+	path = doc/sphinx-bootstrap-theme
+	url = https://github.com/cppformat/sphinx-bootstrap-theme.git
diff --git a/doc/sphinx-bootstrap-theme b/doc/sphinx-bootstrap-theme
new file mode 160000
index 00000000..4cf6be85
--- /dev/null
+++ b/doc/sphinx-bootstrap-theme
@@ -0,0 +1 @@
+Subproject commit 4cf6be855af136d121f8e5bc06ce9621881a06fb