Rails 3.2 with many stylesheet assets in dev mode => error with IE HTC-behaviours

(FYI: I first posted this question at StackOverflow a couple of days ago
without any luck.)

I am developing a new web application in Rails 3.2. I have come to the
point where I am trying to make everything look as nice in IE as
Firefox/Chrome etc.

For that I am using CSS3 PIE http://css3pie.com/

However: Because of the way stylesheets are fragmented out in many small
files, I now have 64 stylesheet files to load in development mode. This
creates a problem in IE, when css3pie.htc tries to dynamically create a
new styleshhet. IE only supports 31 concurrent stylesheets.

Is there a way to make Rails always concatenate all stylesheets into
application.css? In development mode of course. I've tried to manually
run rake assets:precompile, but I cannot get Rails to serve the
precompiled stylesheet instead. Is there some config parameter, that I'm
missing?

/ Carsten

Set config.assets.debug = false in config/development.rb