diff --git a/phpBB/adm/style/admin.css b/phpBB/adm/style/admin.css
index 68c5645d9c..f644adb0d4 100644
--- a/phpBB/adm/style/admin.css
+++ b/phpBB/adm/style/admin.css
@@ -1288,8 +1288,10 @@ input.button1:focus, input.button2:focus, input.button3:focus {
 	position: fixed;
 	display: none;
 	top: 150px;
-	left: 25%;
-	width: 50%;
+	left: 0;
+	right: 0;
+	max-width: 600px;
+	margin: 0 auto;
 	z-index: 50;
 	padding: 25px;
 	padding: 0 25px 20px 25px;
@@ -1345,6 +1347,21 @@ input.button1:focus, input.button2:focus, input.button3:focus {
 	opacity: 0.5;
 }
 
+@media only screen and (max-height: 500px), only screen and (max-device-width: 500px)
+{
+	.phpbb_alert {
+		top: 25px;
+	}
+}
+
+@media only screen and (max-width: 700px), only screen and (max-device-width: 700px)
+{
+	.phpbb_alert {
+		max-width: none;
+		margin: 0 25px;
+	}
+}
+
 /* Pagination
 ---------------------------------------- */
 .pagination {