In light of the nice comments on my previous post on this topic I’m going to share how I’m doing this now, it’s a little easier to manage for me, at least and may be for others.

I’m adding this to functions.php instead of the my_render_ie_pie function I used before, using the WordPress function wp_enqueue_style, the preferred way to add styles to the rendered page:

And then ie8.css just has this, a list of styles that need border radius or some other CSS3 feature:

Notice that all elements that need PIE must have position: relative.

ie7.css is longer (surprise!) but has the same section as above.

I find this easier to get my head around, plus it cleans up functions.php and loads IE stylesheets the proper way.