diff --git a/docs/stylesheets/extra.css b/docs/stylesheets/extra.css
index c10014e5..a7fee9e0 100644
--- a/docs/stylesheets/extra.css
+++ b/docs/stylesheets/extra.css
@@ -9,3 +9,9 @@ img {
 .md-typeset__table table:not([class]) {
   display: table;
 }
+
+h2, h3, h4 {
+  padding: 0.5em 0;
+  text-align: center;
+  background-color: rgba(0, 0, 0, 0.5);
+}