Version: 1.1.alpha.0
Source on Github

CSS3 Pie


CSS PIE is a javascript library that enhances Internet Explorer to render many modern CSS3 capabilities wherever possible. To install:

compass install compass/pie

This will install an example stylesheet and a PIE.htc behavior file that must be loaded into your pages for IE. This file must be delivered with the following mime-type:

Content-Type: text/x-component


The example stylesheet will walk you through setting up your project with css3pie support.

Properties Supported

The following css3 properties are supported:

  • border-radius
  • box-shadow
  • border-image
  • background (in the form of -pie-background, use the background mixin)

Additionally, PIE supports the following CSS3 features:

  • rgba color values
  • linear gradients in backgrounds

Full Documentation on Supported Properties


  1. PIE only understands shortcut properties, long-hand properties don't work because the code, in order to be fast, does not attempt to resolve the stylesheet cascade and so it cannot determine which order to apply the long-hand properties.
  2. Each element that has a PIE behavior attached adds about 10ms to the page render time. Moderation is recommended.
  3. PIE generates content that contains the css3 graphical elements. It has to insert this content into your page and so it needs a little help from you. You have two choices:
    1. You can make your element position: relative.
    2. You can give your element a z-index. If you do this you should also give apply a z-index to an ancestor element that comes before or itself has a background. The compass mixins below and the example stylesheet will help get you set up.

Best Practices

It is suggested that you use Sass's @extend directive to mark elements as PIE elements. The example stylesheet you get when you install compass/pie into your project will walk you through the process of setting that up.


  • For more information see the css3pie website.
  • CSS PIE is written by and copyright to: Jason Johnston
  • Compass is using css3pie version 1.0-beta3. It can be upgraded by downloading a new behavior file and replacing the one that comes with compass.

This file can be imported using: @import "compass/css3/pie"