Stylus is a dynamic stylesheet preprocessor language that is compiled into CSS. It aims to add functionality to CSS without breaking compatibility across web browsers. It does this using variables, nesting, mixins, functions and more.

Stylus syntax is very flexible. You can use standard CSS syntax and leave the semicolon (;), colon (:) and even the ({) and (}) optional, making your code even more readable.

Stylus does not provide new style options, but gives functionality that lets you make your CSS much more dynamic.

Code style

body {
  color: #000;
}

body {
  color: #000
}

body {
  color #000
}

body
  color #000

body
  color: #000;

body
  color: #000

Selectors

Selecting elements within another element.

body {
  color: #000000;
  h1 {
    color: #FF0000;
  }
}

/* Or if you prefer... */
body
  color #000000
  h1
    color #FF0000

Getting parent element reference

a {
  color: #0088dd;
  &:hover {
    color: #DD8800;
  }
}

Variable

You can store a CSS value (such as the color) of a variable. Although it is optional, it is recommended to add $ before a variable name so you can distinguish a variable from another CSS value.

$primary-color = #A3A4FF
$secondary-color = #51527F
$body-font = 'Roboto', sans-serif

/* You can use variables throughout your style sheet.
Now, if you want to change the color, you only have to make the change once. */

body
    background-color $primary-color
    color $secondary-color
    font-family $body-font

/* After compilation: */
body {
    background-color: #A3A4FF;
    color: #51527F;
    font-family: 'Roboto', sans-serif;
}

/ *
This is much easier to maintain than having to change color
each time it appears throughout your style sheet.
* /

Mixins

If you find that you are writing the same code for more than one element, you may want to store that code in a mixin.

center()
  display block
    margin-left auto
    margin-right auto
    left 0
    right 0

/* Using the mixin */
body {
  center()
  background-color: $primary-color
}

/* After compilation: */
div {
    display: block;
    margin-left: auto;
    margin-right: auto;
    left: 0;
    right: 0;
    background-color: #A3A4FF;
}

You can use mixins to create a shorthand property.

size($width, $height)
  width $width
  height $height

.rectangle
  size(100px, 60px)

.square
    size(40px, 40px)

You can use a mixin as a CSS property

circle($ratio)
  width $ratio * 2
  height $ratio * 2
  border-radius $ratio

.ball
  circle 25px

Interpolation

vendor(prop, args)
  -webkit-{prop} args
  -moz-{prop} args
  {prop} args

border-radius()
  vendor('border-radius', arguments)

box-shadow()
  vendor('box-shadow', arguments)

button
  border-radius 1px 2px / 3px 4px

Functions

Functions in Stylus allow you to perform a variety of tasks, such as recalling some data.

body {
  background darken(#0088DD, 50%) // Dim color #0088DD by 50%
}

/* Creating your own function */
add(a, b)
  a + b

body
  padding add(10px, 5)

Conditions

compare(a, b)
  if a > b
    bigger
  else if a < b
    smaller
  else
    equal

compare(5, 2)   // => bigger
compare(1, 5)   // => smaller
compare(10, 10) // => equal

Iterations

/*
Repeat loop syntax for:
for <val-name> [, <key-name>] in <expression>
*/

for $item in (1..2) /* Repeat block 12 times */
  .col-{$item}
    width ($item / 12) * 100% /* Calculate row by column number */

Now that you know a little about this powerful CSS preprocessor, you’re ready to create more dynamic style sheets. To learn more, visit the official stylus documentation at http://stylus-lang.com.

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