diff --git a/Resources.php b/Resources.php
index 32afbe277..8f18715f0 100644
--- a/Resources.php
+++ b/Resources.php
@@ -105,6 +105,9 @@ $wgResourceModules += array(
 			'minerva' => array(
 				'styles/mw.echo.ui.overlay.minerva.less',
 			),
+			'monobook' => array(
+				'styles/mw.echo.ui.overlay.monobook.less',
+			)
 		),
 		'dependencies' => array(
 			'ext.echo.logger',
diff --git a/modules/styles/mw.echo.ui.overlay.monobook.less b/modules/styles/mw.echo.ui.overlay.monobook.less
new file mode 100644
index 000000000..c67c2516b
--- /dev/null
+++ b/modules/styles/mw.echo.ui.overlay.monobook.less
@@ -0,0 +1,8 @@
+.mw-echo-ui-overlay {
+	// We need the overlay to be adjusted for:
+	// #globalWrapper 127%
+	// .pBody 95%
+	// .portlet ul 95%
+	// .mw-echo-ui-notificationBadgeButtonPopupWidget > .oo-ui-popupWidget 0.875/0.75em
+	font-size: 1.27*0.95*0.95*0.875/0.75em;
+}