I've got a stylesheet with font-face. When I minify the css using online services, the font-face stops working. The approach I've taken is the to extract the font-face code, minify the rest of the css and then stick the font-face at the top of the minified stylesheet. Curious if anyone has a better approach to this.
Here's my code: http://snipt.org/zfAj5
I used this service to minify my code: http://www.minifycss.com/css-compressor/
If the tool you're using to minify CSS can't minify CSS, throw it out and get a better tool.
YUI Compressor is a good minification tool for both CSS and JavaScript
I've found using the Google Chrome Page Speed plugin to minify my CSS helps avoid issues like this. It doesn't minify CSS as extremely as some other programs do, but I never run into browser rendering issues either.
I currently have a few stylesheets with @font-face in them minified using this approach:
Source: http://gomakethings.com/how-to-trick-out-the-performance-of-your-wordpress-site/
minifybeautify.com should do the job ... it is instant and simple!