diff --git a/docs/requirements.txt b/docs/requirements.txt
index 2fa8c99770..920bae2662 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1 +1 @@
-mkdocs==1.2.4
+mkdocs==1.3.1
diff --git a/docs/theme/zentral.css b/docs/theme/zentral.css
index 4e98f9e576..02ffff9f41 100644
--- a/docs/theme/zentral.css
+++ b/docs/theme/zentral.css
@@ -4,5 +4,8 @@
 .wy-nav-top {
   background-color: rgb(225, 113, 97);
 }
+.wy-menu-vertical header, .wy-menu-vertical p.caption {
+  color: #9b9b9b;
+}
 table {margin-bottom: 24px;}
 td, th {padding: 12px;}