diff --git a/node_modules/architect-build/build.js b/node_modules/architect-build/build.js
index 14ea79f8..22ee6d5d 100644
--- a/node_modules/architect-build/build.js
+++ b/node_modules/architect-build/build.js
@@ -200,6 +200,14 @@ function compileLess(opts, sources, callback) {
 }
 
 
+function addCssPrefixes(css) {
+    return css.replace(/\b(user-select|font-smoothing)\b([^;\n]+);?/g, function(_, prop, value, index, string) {
+        if (prop[0] == "u" && string[index - 1] != "-") {
+            return "-webkit-" + prop + value + "; -moz-" + prop + value + "; -ms-" + prop + value + "; " + _;
+        }
+        return _;
+    });
+}
 
 function toCss(tree, imports, options, callback) {
     var less = require("less");
@@ -211,6 +219,7 @@ function toCss(tree, imports, options, callback) {
     catch (err) {
         return callback(err);
     }
+    css = addCssPrefixes(css);
     callback(null, css);
 }
 
diff --git a/plugins/c9.ide.ace.statusbar/skin.xml b/plugins/c9.ide.ace.statusbar/skin.xml
index 5844a32b..3794fc52 100644
--- a/plugins/c9.ide.ace.statusbar/skin.xml
+++ b/plugins/c9.ide.ace.statusbar/skin.xml
@@ -72,7 +72,7 @@
                 cursor              : pointer;
                 position            : relative;
                 cursor              : default;
-                .user-select(none);
+                user-select: none;
                 background-position : 0 0;
                 background-repeat   : no-repeat;
                 margin: @ace-status-icon-margin !important;
diff --git a/plugins/c9.ide.collab/timeslider/timeslider.css b/plugins/c9.ide.collab/timeslider/timeslider.css
index dfb72eda..b3ce1687 100644
--- a/plugins/c9.ide.collab/timeslider/timeslider.css
+++ b/plugins/c9.ide.collab/timeslider/timeslider.css
@@ -320,7 +320,7 @@
 }
 
 #ui-slider-handle when(@time-slider-handle-basic = false) {
-    .user-select(none);
+    user-select: none;
 }
 
 #ui-slider-handle span when(@time-slider-handle-basic = false){
@@ -380,7 +380,7 @@
 }
 
 #ui-slider-bar {
-    .user-select(none);
+    user-select: none;
     cursor: pointer;
     height: 35px;
     margin-left: @time-slider-bar-margin-left;
diff --git a/plugins/c9.ide.find.replace/skin.xml b/plugins/c9.ide.find.replace/skin.xml
index 186c94ea..f6ed6501 100644
--- a/plugins/c9.ide.find.replace/skin.xml
+++ b/plugins/c9.ide.find.replace/skin.xml
@@ -6,7 +6,7 @@
                 height             : 22px;
                 cursor             : pointer;
                 position           : absolute;
-                .user-select(none);
+                user-select: none;
                 width              : 20px;
             }
             .btnquicksearchnav .lbl{
diff --git a/plugins/c9.ide.language.core/complete.css b/plugins/c9.ide.language.core/complete.css
index 6a488ad0..c40273e8 100644
--- a/plugins/c9.ide.language.core/complete.css
+++ b/plugins/c9.ide.language.core/complete.css
@@ -216,5 +216,5 @@
 /* allow selecting in doc popup but do not elsewhere */
 .panelsbar, .btnsesssioncontainer, .bar-status, .splitgrabber, 
 .code_complete_text, .ace_scrollbar, .ace_tree {
-    .user-select(none);
+    user-select: none;
 }
\ No newline at end of file
diff --git a/plugins/c9.ide.layout.classic/less/browser-btn.less b/plugins/c9.ide.layout.classic/less/browser-btn.less
index 3f9c9862..191572d3 100644
--- a/plugins/c9.ide.layout.classic/less/browser-btn.less
+++ b/plugins/c9.ide.layout.classic/less/browser-btn.less
@@ -9,7 +9,7 @@
     background-position : 0 27px;
     background-repeat   : no-repeat;
     background-image    : url("@{image-path}/browser_button.png");
-    .user-select(none);
+    user-select: none;
 }
 
 .browser-btn span{
diff --git a/plugins/c9.ide.layout.classic/less/btn-switcher.less b/plugins/c9.ide.layout.classic/less/btn-switcher.less
index 2a47209f..5bbca055 100644
--- a/plugins/c9.ide.layout.classic/less/btn-switcher.less
+++ b/plugins/c9.ide.layout.classic/less/btn-switcher.less
@@ -1,5 +1,5 @@
 .btn-switcher {
-    .user-select(none);
+    user-select: none;
     display: flex;
     align-items: center;
     cursor: default;
diff --git a/plugins/c9.ide.layout.classic/less/btn_console.less b/plugins/c9.ide.layout.classic/less/btn_console.less
index 3f19016f..fe124e3c 100644
--- a/plugins/c9.ide.layout.classic/less/btn_console.less
+++ b/plugins/c9.ide.layout.classic/less/btn_console.less
@@ -1,7 +1,7 @@
 .btn_console {
     width: 20px;
     height: 20px;
-    .user-select(none);
+    user-select: none;
 
     box-sizing: border-box;
     border-radius: 3px;
diff --git a/plugins/c9.ide.layout.classic/less/btn_console_open.less b/plugins/c9.ide.layout.classic/less/btn_console_open.less
index 0387a5d1..ced14490 100644
--- a/plugins/c9.ide.layout.classic/less/btn_console_open.less
+++ b/plugins/c9.ide.layout.classic/less/btn_console_open.less
@@ -5,7 +5,7 @@
     height: 31px;
     width: 18px;
     padding: 6px 4px 8px 5px;
-    .user-select(none);
+    user-select: none;
 }
 
 .btn_console_open span{
diff --git a/plugins/c9.ide.layout.classic/less/btn_icon_only.less b/plugins/c9.ide.layout.classic/less/btn_icon_only.less
index 1f5db69e..cd6ba9bd 100644
--- a/plugins/c9.ide.layout.classic/less/btn_icon_only.less
+++ b/plugins/c9.ide.layout.classic/less/btn_icon_only.less
@@ -4,7 +4,7 @@
     position           : relative;
     height             : 21px;
     width              : 22px;
-    .user-select(none);
+    user-select: none;
 }
 
 .btn_icon_onlyDown.tabmenubtn {
diff --git a/plugins/c9.ide.layout.classic/less/button.less b/plugins/c9.ide.layout.classic/less/button.less
index 8b06a9c1..4bab093e 100644
--- a/plugins/c9.ide.layout.classic/less/button.less
+++ b/plugins/c9.ide.layout.classic/less/button.less
@@ -5,7 +5,7 @@
     cursor             : default;
     position           : relative;
     line-height        : 17px;
-    .user-select(none);
+    user-select: none;
 }
 
 .btn.smallbtn {
diff --git a/plugins/c9.ide.layout.classic/less/c9-menu-bar.less b/plugins/c9.ide.layout.classic/less/c9-menu-bar.less
index 274a5642..4ce4c251 100644
--- a/plugins/c9.ide.layout.classic/less/c9-menu-bar.less
+++ b/plugins/c9.ide.layout.classic/less/c9-menu-bar.less
@@ -1,7 +1,7 @@
 .c9-menu-bar {
     position      : relative;
     overflow      : visible;
-    .user-select(none);
+    user-select: none;
 }
 .c9-menu-bar:before{
     position: absolute;
diff --git a/plugins/c9.ide.layout.classic/less/c9-menu-btn.less b/plugins/c9.ide.layout.classic/less/c9-menu-btn.less
index c8ec388d..9b4125b0 100644
--- a/plugins/c9.ide.layout.classic/less/c9-menu-btn.less
+++ b/plugins/c9.ide.layout.classic/less/c9-menu-btn.less
@@ -14,7 +14,7 @@
     text-shadow   : @menu-button-text-shadow;
     
     
-    .user-select(none);
+    user-select: none;
 }
 
 .c9-menu-btnOver {
diff --git a/plugins/c9.ide.layout.classic/less/c9-simple-btn.less b/plugins/c9.ide.layout.classic/less/c9-simple-btn.less
index c620e6fe..e0a136be 100644
--- a/plugins/c9.ide.layout.classic/less/c9-simple-btn.less
+++ b/plugins/c9.ide.layout.classic/less/c9-simple-btn.less
@@ -1,5 +1,5 @@
 .c9-simple-btn {
-    .user-select(none);
+    user-select: none;
     cursor: default;
 }
 
diff --git a/plugins/c9.ide.layout.classic/less/c9-toolbarbutton.less b/plugins/c9.ide.layout.classic/less/c9-toolbarbutton.less
index f689f17b..fe690021 100644
--- a/plugins/c9.ide.layout.classic/less/c9-toolbarbutton.less
+++ b/plugins/c9.ide.layout.classic/less/c9-toolbarbutton.less
@@ -6,7 +6,7 @@
     position           : relative;
     line-height        : 17px;
     border:1px solid transparent;
-    .user-select(none);
+    user-select: none;
 }
 
 .with-arrow.c9-toolbarbutton {
diff --git a/plugins/c9.ide.layout.classic/less/editor_tab.less b/plugins/c9.ide.layout.classic/less/editor_tab.less
index 35b2f377..deb20bc0 100644
--- a/plugins/c9.ide.layout.classic/less/editor_tab.less
+++ b/plugins/c9.ide.layout.classic/less/editor_tab.less
@@ -249,7 +249,7 @@ body>.session_btn.curbtn{
     white-space : nowrap;
     overflow : hidden;
     padding  : @pane-button-title-padding;
-    .user-select(none);
+    user-select: none;
     color : @pane-button-color;
     text-shadow : @pane-button-textshadow;
     // position: relative;
diff --git a/plugins/c9.ide.layout.classic/less/frame.less b/plugins/c9.ide.layout.classic/less/frame.less
index 60e469a0..735fc232 100644
--- a/plugins/c9.ide.layout.classic/less/frame.less
+++ b/plugins/c9.ide.layout.classic/less/frame.less
@@ -23,7 +23,7 @@
     color: @frame-title-color;
     background-color: @frame-title-background;
     background-image: linear-gradient(90deg, @frame-title-gradient-start 0%, @frame-title-gradient-stop 100%);
-    .user-select(none);
+    user-select: none;
 }
 .frame>.title:hover{
     background-image: linear-gradient(90deg, @frame-title-gradient-hover-start 0%, @frame-title-gradient-hover-stop 100%);
diff --git a/plugins/c9.ide.layout.classic/less/header-btn.less b/plugins/c9.ide.layout.classic/less/header-btn.less
index ec7335e5..544c17a9 100644
--- a/plugins/c9.ide.layout.classic/less/header-btn.less
+++ b/plugins/c9.ide.layout.classic/less/header-btn.less
@@ -10,7 +10,7 @@
     background-repeat   : no-repeat;
     top                 : 5px;
     z-index             : 1000;
-    .user-select(none);
+    user-select: none;
 }
 .panel-settings {
     background-position: @tree-settings-background;
@@ -60,6 +60,6 @@
     position: absolute;
     top: 0;
     width: 2px;
-    .user-select(none);
+    user-select: none;
 }
     
\ No newline at end of file
diff --git a/plugins/c9.ide.layout.classic/less/lesshat.less b/plugins/c9.ide.layout.classic/less/lesshat.less
index c1af945f..302260e5 100755
--- a/plugins/c9.ide.layout.classic/less/lesshat.less
+++ b/plugins/c9.ide.layout.classic/less/lesshat.less
@@ -5,36 +5,6 @@
 //  Petr Brzek & Jan Kuca
 
 
-//  .size
-
-  .size(@square){
-    width: @square;
-    height: @square;
-  }
-
-  .size(@width, @height){
-    width: @width;
-    height: @height;
-  }
-
-    //  element{ .size(10px); } // render width:10px; height:10px;
-    //  element{ .size(10px, 20px); } // render width:10px; height: 20px;
-
-
-
-//  .user-select
-
-  .user-select(@arguments:auto){
-    -webkit-user-select: @arguments;
-    -moz-user-select: @arguments;
-    -ms-user-select: @arguments;
-    user-select: @arguments;
-  }
-
-   //   element{ .user-select(text); }
-
-
-
 .font-smoothing(@state){
     .font-smoothing(@state) when (@state = true) {
         -webkit-font-smoothing: antialiased;
diff --git a/plugins/c9.ide.local/local.less b/plugins/c9.ide.local/local.less
index d2948b0c..5188ca67 100644
--- a/plugins/c9.ide.local/local.less
+++ b/plugins/c9.ide.local/local.less
@@ -30,7 +30,7 @@
     font-size: 13px;
     text-align: center;
     border-radius: 3px 3px 0 0;
-    .user-select(none);
+    user-select: none;
     overflow: hidden;
     -webkit-app-region: drag;
 }
diff --git a/plugins/c9.ide.run.debug/debuggers/socket.js b/plugins/c9.ide.run.debug/debuggers/socket.js
index 40074a7c..a9cc73ea 100644
--- a/plugins/c9.ide.run.debug/debuggers/socket.js
+++ b/plugins/c9.ide.run.debug/debuggers/socket.js
@@ -10,7 +10,7 @@ define(function(require, exports, module) {
         var proc = imports.proc;
         var nodeBin = Array.isArray(options.nodeBin)
             ? options.nodeBin[0]
-            : options.nodeBin || "node";
+            : options.nodeBin || "node"; 
 
         var DISCONNECTED = 0;
         var CONNECTED = 1;
diff --git a/plugins/c9.ide.scm/diff/conflictmarker.css b/plugins/c9.ide.scm/diff/conflictmarker.css
index 639e1a0e..1c18d6ea 100644
--- a/plugins/c9.ide.scm/diff/conflictmarker.css
+++ b/plugins/c9.ide.scm/diff/conflictmarker.css
@@ -57,7 +57,7 @@
 .ace_button {
     margin-left: 2px;
     cursor: pointer;
-    .user-select(none);
+    user-select: none;
     overflow: hidden;
     border: 1px solid rgba(100,100,100,0.23);
     padding: 2px 4px;
diff --git a/plugins/c9.ide.test/style.css b/plugins/c9.ide.test/style.css
index 905a0e10..2123809c 100644
--- a/plugins/c9.ide.test/style.css
+++ b/plugins/c9.ide.test/style.css
@@ -22,7 +22,7 @@
     color: #795A0A;
     margin: 0 5px;
     pointer-events:auto;
-    .user-select(text);
+    user-select: text;
 }
 .stack-message.more{
     cursor:pointer;
diff --git a/plugins/c9.ide.upload/markup/skin.xml b/plugins/c9.ide.upload/markup/skin.xml
index 5e71dcb9..e2b09552 100644
--- a/plugins/c9.ide.upload/markup/skin.xml
+++ b/plugins/c9.ide.upload/markup/skin.xml
@@ -153,7 +153,7 @@
         <a:style><![CDATA[
             .btn-cancel-upload {
                 position            : relative;
-                .user-select(none);
+                user-select: none;
                 color               : #a4a4a4;
                 font-size           : 11px;
                 height              : 14px;