OOCSS and Preprocessors in a Tree, K-I-S-S-I-N-G - Nicole Sullivan at Smashing Conference

17 September 2012

Brad Frost OOCSS and Preprocessors in a Tree, K-I-S-S-I-N-G - Nicole Sullivan at Smashing Conference

In OOCSS and Preprocessors in a Tree, K-I-S-S-I-N-G, Nicole Sullivan explains how to write more modular CSS with SaSS.

Some of Nicole's clients had 100,000 lines of CSS. Nicole helps them whittle it down to 1,500 lines.
You only ever learn about something by doing it wrong the first time. Experience in doing things incorrectly can show you
It's not OOCSS or SaSS. That's the wrong question, they're quite complementary.

OOCSS and SaSS

OOCSS is a way of writing CSS that avoids duplicating CSS
OOCSS is tiny dry awesome CSS, while SaSS is dry awesome SCSS
OOCSS uses multiple classes to simulate inheritance, while SaSS handles it in CSS using @extend
OOCSS doesn't have a good mechanism for mixins, tends to duplicate the code, while SaSS uses @include to simulate mixins
OOCSS is what you want to say, while SaSS is an alternate way of saying it.

Getting Started with SaSS

Sometimes plain CSS solutions are painful. SaSS can help. For example, there are multiple clearfix methods and sometimes certain clearfix solutions work for a module and other times a different solution is more appropriate
Nesting is a good intro to SaSS
It's tempting to make the SaSS nesting match the html. But that results in hefty overly-specific CSS.
Nesting shows (an approximation of) specificity
Be careful with nesting - it can generate a lot of overly-specific styles. Easy to write in SaSS, but easy != good.
Keep an eye on the output file and make sure things aren't getting unruly.
The Inception Rule - Never go more than three levels deep

Mixins

How to Optimize Mixins - Use them when you wouldn't want the class in the html (eg a border radius) and use them for small number of properties

Extends

Building message boxes (error, information, success, other)
Avpods property value pair duplication
Causes selector duplication
best for simple selectors
messy with many nested subsides
messy output when many classes extend another class
OOCSS instead uses multiple classes in the HTML instead of using CSS.
It's OK to use a combination of a use @extend if a relationship is implied. @include if one is not.

Multi-Class Extension

Nicole doesn't see a good reason to use multi-class extensions. It avoids confusion and reduces the output.

Placeholders

When you want to abstract something, but don't need the class itself in the stylesheet. Similar to @include, but doesn't create a class for the 'parent' class.

IE-specific Classes

Make SaSS play nicely with Modernizr
Nicole removed Modernizr and instead uses * and _ hacks. This keeps IE code together with normal code.

Modular SaSS

Not everyone wants all of the code. Author in a way so that the people who want grids will only get the CSS.

Take-aways

Try SaSS, it's a super useful tool
Relentlessly focus on the output, make sure both SaSS and CSS make sense
Use frameworks when appropriate, but only use the stuff you need.