Created tutorial for removing vendor specific prefixes

doc-src/content/help/tutorials/exclude_vendor_prefixes.markdown

@@ -0,0 +1,71 @@
+---
+title: Removing Vendor Prefixes from Compass Stylesheets
+layout: tutorial
+crumb: Removing Vendor Prefixes from Compass
+classnames:
+  - tutorial
+---
+# Removing Vendor Prefixes from Compass Stylesheets
+
+Compass makes it easy to code many of the CSS3 vendor prefixed properties, without having to type it all out by hand.
+
+## Easy Vendor Prefixes
+
+Let's say you wanted to add a border radius to an element like this:
+
+    .round {
+        -moz-border-radius: 4px;
+        -webkit-border-radius: 4px;
+        border-radius: 4px;
+    }
+
+With Compass it's easier to use the `border-radius` mixin:
+
+    .round {
+        @include border-radius(4px);
+    }
+
+That mixin will create all of the vendor prefixed CSS properties you need, with much less of a chance of a typo or inconsistent display. It will also take care of any browser specific implementations of the CSS property that don't match up to the W3C specification.
+    
+    .round {
+        -moz-border-radius: 4px;
+        -webkit-border-radius: 4px;
+        -o-border-radius: 4px;
+        -ms-border-radius: 4px;
+        -khtml-border-radius: 4px;
+        border-radius: 4px;
+    }
+
+## Problem
+
+The problem with that solution, as good as it is, is that all of those browser prefixes will cruft up your stylesheet quickly if you use a lot of them, and/or aren't using `@extend` to keep them to a minimum. 
+
+Of particular note are the generated Opera `(-o-border-radius)` and Konquerer `(-khtml-border-radius)` properties, which are added to create support for those browsers. As great as those browsers may be, they often account for a very small minority of a website's traffic, traffic that may not compensate for the full weight of their support when using experimental CSS3 properties.
+
+## Solution
+
+Thankfully, Compass includes a selection of default boolean variables that you can override, allowing you to globally turn off the support for the various vendor prefixes:
+
+    $experimental-support-for-mozilla : true !default;
+    $experimental-support-for-webkit : true !default;
+    $support-for-original-webkit-gradients : true !default;
+    $experimental-support-for-opera : true !default;
+    $experimental-support-for-microsoft : true !default;
+    $experimental-support-for-khtml : true !default;
+
+If you set any of the above variables to `false`, Compass will skip those prefixes when it processes your stylesheet.
+
+So to exclude Opera and Konquerer vendor prefixes from your CSS, add the following code just above your include of the CSS3 module in your base SCSS file:
+    
+    $experimental-support-for-opera:false;
+    $experimental-support-for-khtml:false;
+    @import "compass/css3";
+
+The resultant output will be as follow:
+
+    .round {
+        -moz-border-radius: 4px;
+        -webkit-border-radius: 4px;
+        -ms-border-radius: 4px;
+        border-radius: 4px;
+    }