Sass

Syntactically Awesome Style Sheets is a CSS pre-processor for Cascading Style Sheets (CSS).

Basics

Introduction

• Documentation (sass-lang.com)
• Learn X in Y minutes (learnxinyminutes.com)

Variables

$defaultLinkColor: #46EAC2;

a {
  color: $defaultLinkColor;
}

String interpolation

$wk: -webkit-;

.rounded-box {
  #{$wk}border-radius: 4px;
}

Comments

/*
 Block comments
 Block comments
 Block comments
*/

// Line comments

Mixins

@mixin heading-font {
    font-family: sans-serif;
    font-weight: bold;
}
h1 {
    @include heading-font;
}

See: Mixins

Nesting

.markdown-body {
    a {
      color: blue;
      &:hover {
        color: red;
      }
    }
}

to properties

text: {
    // like text-align: center
    align: center;          
    // like text-transform: uppercase
    transform: uppercase; 
}

Extend

.button {
    ···
}

.push-button {
    @extend .button;
}

@import

@import './other_sass_file';
@import '/code', 'lists';

// Plain CSS @imports
@import "theme.css";
@import url(theme);

The .sass or .sass extension is optional.

Mixins

Parameters

@mixin font-size($n) {
    font-size: $n * 1.2em;
}

body {
    @include font-size(2);
}

Default values

@mixin pad($n: 10px) {
    padding: $n;
}

body {
    @include pad(15px);
}

Default variable

$default-padding: 10px;

@mixin pad($n: $default-padding) {
    padding: $n;
}

body {
    @include pad(15px);
}

Color functions

rgba

rgb(100, 120, 140)
rgba(100, 120, 140, .5)
rgba($color, .5)

Mixing

mix($a, $b, 10%)   // 10% a, 90% b

Modifying HSLA

darken($color, 5%)
lighten($color, 5%)

saturate($color, 5%)
desaturate($color, 5%)
grayscale($color)

adjust-hue($color, 15deg)
complement($color)    // like adjust-hue(_, 180deg)
invert($color)

fade-in($color, .5)   // aka opacify()
fade-out($color, .5)  // aka transparentize()
rgba($color, .5)      // sets alpha to .5

Getting individual values

HSLA

hue($color)         // 0deg..360deg
saturation($color)  // 0%..100%
lightness($color)   // 0%..100%
alpha($color)       // 0..1 (aka opacity())

RGB

red($color)         // 0..255
green($color)
blue($color)

See: hue(), red()

Adjustments

// Changes by fixed amounts
adjust-color($color, $blue: 5)
adjust-color($color, $lightness: -30%) // darken(_, 30%)
adjust-color($color, $alpha: -0.4)     // fade-out(_, .4)
adjust-color($color, $hue: 30deg)      // adjust-hue(_, 15deg)

// Changes via percentage
scale-color($color, $lightness: 50%)

// Changes one property completely
change-color($color, $hue: 180deg)
change-color($color, $blue: 250)

Supported: $red, $green, $blue, $hue, $saturation, $lightness, $alpha

Other functions

Strings

unquote('hello')
quote(hello)

to-upper-case(hello)
to-lower-case(hello)

str-length(hello world)
str-slice(hello, 2, 5)     // "ello" - it's 1-based, not 0-based
str-insert("abcd", "X", 1) // "Xabcd"

Units

unit(3em)        // 'em'
unitless(100px)  // false

Numbers

floor(3.5)
ceil(3.5)
round(3.5)
abs(3.5)

min(1, 2, 3)
max(1, 2, 3)

percentage(.5)   // 50%
random(3)        // 0..3

Misc

variable-exists(red)    // checks for $red
mixin-exists(red-text)  // checks for @mixin red-text
function-exists(redify)

global-variable-exists(red)

selector-append('.menu', 'li', 'a')   // .menu li a
selector-nest('.menu', '&:hover li')  // .menu:hover li
selector-extend(...)
selector-parse(...)
selector-replace(...)
selector-unify(...)

Feature checks

Feature check

feature-exists(global-variable-shadowing)

Features

• global-variable-shadowing
• extend-selector-pseudoclass
• units-level-3
• at-error

Loops

For loops

@for $i from 1 through 4 {
    .item-#{$i} { left: 20px * $i; }
}

Each loops (simple)

$menu-items: home about contact;

@each $item in $menu-items {
    .photo-#{$item} {
      background: url('#{$item}.jpg');
    }
}

Each loops (nested)

$backgrounds: (home, 'home.jpg'),
              (about, 'about.jpg');

@each $id, $image in $backgrounds {
    .photo-#{$id} {
      background: url($image);
    }
}

While loops

$i: 6;
@while $i > 0 {
    .item-#{$i} { width: 2em * $i; }
    $i: $i - 2;
}

Other features

Conditionals

@if $position == 'left' {
     position: absolute;
     left: 0;
}
@else if $position == 'right' {
     position: absolute;
     right: 0;
}
@else {
     position: static;
}

Interpolation

.#{$klass} { ... }      // Class
call($function-name)    // Functions

@media #{$tablet}
font: #{$size}/#{$line-height}
url("#{$background}.jpg")

Lists

$list: (a b c);

nth($list, 1)  // starts with 1
length($list)

@each $item in $list { ... }

Maps

$map: (key1: value1, key2: value2, key3: value3);

map-get($map, key1)