How do you scale CSS for millions of visitors or thousands of pages? Object Oriented CSS allows you to write fast, maintainable, standards-based front end code. It adds much needed predictability to CSS so that even beginners can participate in writing beautiful websites.

I recently presented Object Oriented CSS for high performance web applications and sites at Web Directions North 2009. If you didn’t attend my talk, you are probably asking yourself “what in the world is OO-CSS?”

Object Oriented CSS: Two main principles

1. Separate structure and skin
2. Separate container and content

I’m writing a framework to demonstrate the technique, but more than anything, Object Oriented CSS is a different way of approaching CSS and the cascade. It draws on traditional software engineering concepts like extending objects, modularity, and predictability. Solutions are judged based on their complexity, in other words, “what happens to the size of the CSS file as more pages and modules are added?”

The answer, for most sites, is that it grows out of control and becomes an unmaintainable tangle of spaghetti code. People often complain about CSS, and rightly so — even though it inspired a rant, I understand their frustration.

Current methods for writing CSS require expert level ability just to get started. To become a CSS expert, you need to spend couple years coding away in your basement by yourself before you are remotely useful. Front-end engineering needs to accomodate entry level, mid level, and architect level developers, but our sites are too brittle. You may have a perfectly accessible or high performance website, and then the first newbie to touch it, ruins it. Our code should be robust enough that newbies can contribute while maintaining the standards we’ve set.

We don’t trust each others code

Imagine a JavaScript developer wrote a function to return area, and every now and then it randomly returned the diameter instead. The function would never make it through a code review, and yet we tolerate the same thing from CSS, as if it were immune from normal programming best-practices. This is why CSS code reuse is almost nonexistent. An object should behave predictably no matter where you place it on the page, which is why Object Oriented CSS avoids location dependent styles.

What not to do

#myModule h2{...}
#myModule span{...}
#myModule #saleModule{...}
#myOtherModule h3{...}
#myOtherModule span{...}

Developers have tried to sandbox their CSS into individual modules, to protect against the cascade. But in doing so we’ve ended up with a mess.

Object Oriented CSS Grids on github

My Object Oriented CSS grids and templates are open sourced on github. They have all the functionality of YUI grids plus some important features.

• Only 4kb, half the size of YUI grids. (I was totally happy when I checked the final size!)
• They allow infinite nesting and stacking.
• The only change required to use any of the objects is to place it in the HTML, there are no changes to other places in the DOM and no location dependent styling. Eases back-end development and makes it a lot easier to manage for newbies.
• Solution for sub-pixel rounding errors.

http://wiki.github.com/stubbornella/oocss

Check out template.css and grids.css and the docs on the github wiki.

My prediction is that you’ll be writing complex layouts in less than 24 hours without adding a line to the CSS file.

What’s up next?

Template and grids are ready for rock and roll. Please be my alpha testers, put them through their paces. Let me know if you find bugs or want additional functionality. I’m also hoping to contribute some of this back to YUI since they now have a github repository. How cool is that?

Rounded Corner Boxes and Tabs

Next up, modules. There are a million cool ways to create rounded corner boxes. I’m going to take several of my favorites (like CSS Mojo and Arnaud Gueras blocks) and convert them to OO-CSS. This will make it super easy for newbies to create their own modules, without needing to understand the minutiae of browser differences.

Video / Podcasts

YDN will publish a video of my talk and Web Directions North is putting out podcasts. I’ll tweet and post when that happens. The audio contains a lot more detail than the slides, so check it out as they become available.