Remove excessive 5% left-padding and replace with consistent padding

This gives more space to display/input setting panels and is more
consistent with the padding on the left-side menu as well.

Bug: T136273
Change-Id: I5c0e5e351e370c4c0b19783edc8278250ca3ca76

resources/css/ext.uls.languagesettings.css

@@ -42,7 +42,7 @@
 }
 
 #languagesettings-settings-panel {
-	padding-left: 5%;
+	padding: 0 15px;
 	color: #252525;
 	background: #fff;
 	border-bottom-right-radius: 5px;