What is it?
IE-CSS3 is a script to provide Internet Explorer support for some new styles available in the upcoming CSS3 standard.
How it works
If you’re viewing this page in Internet Explorer, some of the elements have been rebuilt by the script in Vector Markup Language (VML), an IE-specific vector drawing language. VML supports things that are missing from IE’s CSS implementation like rounded corners and blur effects.
How to use it
Just add CSS styles as you normally would, but include one new line:
-moz-border-radius: 15px; /* Firefox */
-webkit-border-radius: 15px; /* Safari and Chrome */
border-radius: 15px; /* Opera 10.5+, future browsers, and now also Internet Explorer 6+ using IE-CSS3 */
-moz-box-shadow: 10px 10px 20px #000; /* Firefox */
-webkit-box-shadow: 10px 10px 20px #000; /* Safari and Chrome */
box-shadow: 10px 10px 20px #000; /* Opera 10.5+, future browsers and IE6+ using IE-CSS3 */
behavior: url(ie-css3.htc); /* This lets IE know to call the script on all elements which get the ‘box’ class */
Issues and Workarounds
You would expect URLs in behavior: url(…) to be relative to the current directory as they are in a background-image: url(…) style for example, but instead Microsoft decided to ignore standards here and make them relative to the docroot instead. So behavior: url(ie-css3.htc) should work if ie-css3.htc is in the root directory of the site.
You will probably run into issues with z-index, especially if embedding one IE-CSS3 enabled element inside of another. There are two simple workarounds:
Set the z-index of the IE-CSS3 element to a number larger than its surrounding elements.
Make sure the IE-CSS3 element is positioned, such as with position: relative or position: absolute
Sometimes an IE-CSS3 element will show up at a slightly different position than the original, untouched element. There could be a few reasons for this:
You have broken tags somewhere in your markup, probably above the IE-CSS3 element.
You are experiencing misc IE6 and IE7 bugs. Try adding the styles zoom: 1 and/or position: relative to the IE-CSS3 element and its immediate parent. You could also try removing any margins on the IE-CSS3 element and/or its parent, use padding instead.
Styles and their status
Style What works What doesn’t work
Setting a radius for all four corners
Setting a radius for individual corners separately
Any color other than #000
The shadow looks a little bit different than it does in FF/Safari/Chrome, I’m not sure why