CSS Preprocessors. Comparing SASS, LESS and Stylus

CSS Preprocessors
Sass, Less and Stylus
Patrick Arlt - @patrickarlt

Some Background
I'm an Designer and Developers at Geoloqi Esri.
Design, UX, HTML, CSS, JS, lots of it everyday...

Ok Ok, which is best?
Really Short Answer
SASS or Stylus
Slightly Longer Answer
SASS if you are using Ruby. Stylus if you using Node. LESS if
you afraid of the command line.

80/20
80% of SASS, LESS and Stylus is the same.
The 20% that is different is in advanced usage.

Installing
SASS
LESS
Stylus
$ gem install sass
$ sass --watch style.scss:style.css
<link rel="stylesheet/less" type="text/css" href="styles.less">
<script src="less.js" type="text/javascript"></script>
$ npm install less
$ lessc styles.less
$ npm install stylus
$ stylus css --watch

The 80%
Variables
Color Transformation
Mixins
Nesting
Loops & Conditionals
Importing

Variables
SASS
LESS
Stylus
$button-background: #27adec;
.btn {
background: $button-background;
}
@button-background: #27adec;
.btn {
background: @button-background;
}
button-background = #27adec
.btn
background button-background

Color Transformations
SASS
LESS
Stylus
lighten(@color, 10%);
mix($dark-blue, $light-blue, 25%);
body
color: #444 + #111;

Without Params With Params
LESS Mixins
.bordered {
border: 1px solid #000;
border-top-color: #444;
border-bottom-color: #444;
}
#main {
.bordered;
}
.border-radius (@r) {
-webkit-border-radius: @r;
-moz-border-radius: @r;
border-radius: @r;
}
#main {
.border-radius(4px);
}

SASS Mixins
@mixin border-radius ($radius: 5px) {
-webkit-border-radius: $radius;
-moz-border-radius: $radius;
border-radius: $radius;
}
#main {
@include border-radius(4px);
}

Stylus Mixins
border-radius(n)
-webkit-border-radius n
-moz-border-radius n
border-radius n
#main
border-radius(5px)

Nesting
You can nest selectors in all three frameworks.
#main{
margin: 0 auto;
.title {
font-size: 4em;
}
a {
text-decoration: none;
&:hover {
text-decoration: underline;
}
}
}

Imports
All 3 support importing from other files or libraries...
@import "compass/css3";
@import "susy";
@import "animation/animate";
@import "myfile.scss";
#main {
@include border-radius(5px); // from compass/css3
@include span-columns(10); // from susy
@include animation(fadeIn); // from animation/animate
background: $background-color; // from myfile.scss
}
#sidebar {
@include span-columns(2 omega); // from susy
}

More Features
Conditionals like "if, "when"
MATH!
SASS and Stylus
Loops like "for", "while", and "each"
Much more depth then LESS
Custom functions without the Ruby/JS API

@extend
.button {
background: $blue;
color: #fff
}
.my-special-button {
@extend .button;
font-size: 2em;
}
.button, .my-special-button {
background: $blue;
color: #fff
}
.my-special-button {
font-size: 2em;
}

@extend Selectors
// This won't be compiled
#context a%extreme {
color: red;
font-weight: bold;
font-size: 2em;
}
.notice {
@extend %extreme;
}
#content a.notice {
color: $red;
font-weight: bold;
font-size: 2em;
}

@media
Declare media queries inside selectors
#content {
width: 65%;
margin: 0 auto;
@media only screen and (max-width : 767px) {
width: 90%;
}
}
#content {
width: 65%;
margin: 0 auto;
}
@media only screen and (max-device-width : 768px) {
#content {
width: 90%;
}
}

@content
My favorite SASS feature. Lets you pass whole style blocks
into mixins. Similar to Rubys "yeild". Use it for...
Media Query Helpers
Retina Images
IE Specific Styles
CSS3 Polyfills

@content Example


<html lang="en">
@mixin for-ie(){
html.ie &{
@content;
}
}
#browser-warning {
display:none;
@include for-ie(){
display:block
}
}

Compass
makes SASS even more awesome
CSS3 mixins, supports almost every CSS3 feature
Typography styling helpers
Generates CSS sprites
Produces cross browser CSS for IE6,7,8
Plugin framework via Rubygems
Compass
Compass Bootstrap
Foundation Framework
Susy - Responsive Grids
Compass Animation

LESS
Mixins
Namespaces
Scoped Variables
Client Side Processing

Mixins
In LESS every class is a mixin
.clearfix() {
zoom: 1;
&:before { content: ''; display: block; }
&:after { content: ''; display: table; clear: both; }
}
#content {
.clearfix();
}

Namespaceing Mixins
Organize your mixins into namespaces
#my-framework {
.button () {
display: block;
border: 1px solid @dark-blue;
background-color: @blue;
color: @light-blue;
}
}
.a-button {
#my-framework > .button;
}

Scoped Variables
Variables have scope which makes them it easy to override
@text-color: #444;
@background-color: #fafafa;
body {
color: @text-color;
background: @background-color;
}
.inverse {
@text-color: #fafafa;
@background-color: #444;
color: @text-color;
background: @background-color;
}
h1 { color: @text-color + #111; }

Client-Side Compiling
Great for static HTML sites
Sites where you don't have a real server (S3)
You can evaluate Javascript in your .less files
Evalute Javascipt
You can evalute a javascript expression as a variable
@height: `document.body.clientHeight`;
@width: `document.body.clientWidth`;

Stylus
Syntax
Language Features
@keyframes
Javascript API

Stylus Syntax
Whitespace Based
Can omit { : ; }
The biggest problem I have with Stylus is with its syntax
border-radius()
-webkit-border-radius arguments
-moz-border-radius arguments
border-radius arguments
body
font 12px Helvetica, Arial, sans-serif
a.button
border-radius(5px)

Stylus Language
Stylus feels very much like a simple programming language
Ruby-like ranges [1..5], [0...5]
for/in loops
real operator precidence
complex conditionals if/else if/else, unless/else, postfix
conditionals

@keyframe Support
CSS3 keyframes are awesome, Stylus makes then easy
This is awesome!
@keyframes pulse
0%, 100%
-webkit-transform translateX(0);
20%, 60%
-webkit-transform translateX(-10px);
40%, 80%
-webkit-transform translateX(10px);

Javascript API
You could do a whole talk on the Stylus API, here are some
ideas...
Declare really custom functions
Use Node modules like canvas
Do Compass-like sprite generation
Create your own CSS framework

Nib
CSS3 helpers - gradiants, border-radius, ect...
Mixins for common css patterns
Extends CSS with new properties and values
#feedback
fixed: bottom right
#logo
image: '/img/logo.png'
h1
overflow: ellipsis

LESS Looses
LESS just doesn't have the features or power of SASS or
Stylus
Nothing like Compass or Nib
No plugin system
Can't define your own functions with just LESS
Doesn't output any debugging info

SASS vs. Stylus
Both have similar features, a powerful plugin ecosystem,
and lots of CSS3 helpers.
SASS syntax is close to CSS
Stylus is closer to a programming language
If you use Ruby you will probally use SASS
If you use Node you will probally use Stylus

Questions
Patrick Arlt - @patrickarlt

CSS Preprocessors. Comparing SASS, LESS and Stylus

CSS Preprocessors. Comparing SASS, LESS and Stylus

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