diff --git a/static/scss/custom.scss b/static/scss/custom.scss
index a19ee53699cfdd4a9fbe0fef3b359490a666ac0b..9ce673073c06bf8b3b995dc6120b1cbc78d08a81 100644
--- a/static/scss/custom.scss
+++ b/static/scss/custom.scss
@@ -644,3 +644,11 @@ body.login #content_body .row > div.col-md-9 > p + div.container {
   display: block;
   font-variant: small-caps;
 }
+
+table.calendar, table.calendar td:empty {
+  background-color: lightgray;
+}
+
+table.calendar th, table.calendar td {
+  background-color: #fff;
+}