diff --git a/themes/quark-open-publishing/css/custom.css b/themes/quark-open-publishing/css/custom.css
index a29720f9..29f62194 100644
--- a/themes/quark-open-publishing/css/custom.css
+++ b/themes/quark-open-publishing/css/custom.css
@@ -35,3 +35,8 @@
 	font-size: .5em;
 	color: #1d66bf;
 }
+
+body {
+    max-width: 1920px;
+    margin: 0 auto; /* center the content horizontally */
+}