In that same CSS rule, add the following style line:
behavior: url(path/to/PIE.htc);
Of course you will need to adjust the path to match where you uploaded PIE.htc in step 2. Note: this path is relative to the HTML file being viewed, not the CSS file it is called from.
but if my url is domain.com/foo/foo.html PIE.htc is not loaded any more if i use
behavior: url(PIE.htc);
PIE.htc is located in root. Can i somehow always call .htc file from root?
URIs starting with a /
are relative to the site root.