Published February 29, 2012

Bless this CSS Mess with Compass

My workaround for using Bless with Compass & Sass

I reached a small, nightmarish victory yesterday while testing some new styles on HipHost in IE: two of my CSS files surpassed Internet Explorer's CSS Selector Limit for a single stylesheet file: 4095.



Hm? What's this?


Bless is a node.js module that checks a CSS file for the IE selector limit. If it reaches it, it breaks it into smaller files and then links them all with @imports in the original foo.css file.

But we're not running node.js. :(

After extensive Googling, there's no good equivalent or port of Bless for Compass, Sass, Rails, or even straight Ruby.

From Compass to Bless

As a Compass user, my ideal scenario would be to run a Ruby version of Bless after every compile. A reasonable alternative would be to pass the Compass output to Bless.

Luckily there is a way to configure a callback in our compass.rb, so that certainly puts us on the right path:

on_stylesheet_saved do |filename|
    # do something with fileneame

We can then run the Bless executable (blessc) like this:

on_stylesheet_saved do |filename|

In the immortal words of the Apache placeholder DocumentRoot: "It works!"

Requisite Gotcha

For HipHost, we're still on Rails 3.0. That means no asset pipeline, so we're using the asset packager gem.

For produciton, asset packager takes the stylesheet groups you've defined and concatenates and minifies them. It calls these files groupname_packaged.css, which of course screws up the @import directives Bless was kind enough to create.

My solution was to make a new stylesheet group for fooblessed1 so at least the Blessed @imports are minified and created for production. I then just go into foopackaged.css and manually update the path for fooblessed1.css to fooblessed1_packaged.css.

UPDATE: Did it.

in vendor/plugins/asset_packager/lib/synthesis/asset_package.rb find the method compress_css and add the following:


I'm no Ruby developer…

I took a quick stab at hacking asset_packager to do this for me, but gave up having spent too much time working on this already. Anything I accomplish will probably be pretty specific to our needs and not be worth open-sourcing, but I'll certainly share my success when it happens.

Mixing Rails and Node.js

This approach obviously creates a non-gem dependency situation for our app. But installing node.js on any major package management system is as to easy to worry much about it:

brew/apt-get/yum install node
curl | sh

Better solution?

Ping me if you have some ideas. Porting Bless to Ruby feels like the cleanest solution, but I may be wrong. If there's a better way to glue node modules as dependencies to Rails apps, that could be it too.