Obviously it won't make it impossible to decipher, just harder (and perhaps not worth the effort). If the line order of each statement is also randomized and useless attributes are added, they'd have to pretty much compile the CSS and compare the attributes.
The alternative way to beat all email obfuscation techniques is of course taking a snapshot and running OCR on it, but certainly not worth the effort/CPU time.
Not as much effort as you might think. Command-line rendering of html (including css and js) and taking a screenshot is not very difficult. If a site used this method, and someone is highly motivated to break that captcha, the effort put in would be nothing compared to the benefit of bypassing the "security".
The alternative way to beat all email obfuscation techniques is of course taking a snapshot and running OCR on it, but certainly not worth the effort/CPU time.