closes #6236

public/language/en-GB/admin/appearance/customise.json

@@ -1,7 +1,7 @@
 {
-	"custom-css": "Custom CSS",
-	"custom-css.description": "Enter your own CSS declarations here, which will be applied after all other styles.",
-	"custom-css.enable": "Enable Custom CSS",
+	"custom-css": "Custom CSS/LESS",
+	"custom-css.description": "Enter your own CSS/LESS declarations here, which will be applied after all other styles.",
+	"custom-css.enable": "Enable Custom CSS/LESS",
 
 	"custom-js": "Custom Javascript",
 	"custom-js.description": "Enter your own javascript here. It will be executed after the page is loaded completely.",

public/src/admin/appearance/customise.js

@@ -14,7 +14,7 @@ define('admin/appearance/customise', ['admin/settings', 'ace/ace'], function (Se
 			var customHTML = ace.edit('customHTML');
 
 			customCSS.setTheme('ace/theme/twilight');
-			customCSS.getSession().setMode('ace/mode/css');
+			customCSS.getSession().setMode('ace/mode/less');
 
 			customCSS.on('change', function () {
 				app.flags = app.flags || {};