Variables

We may assign expressions to variables and use them throughout our stylesheet:

font-size = 14px

body
  font font-size Arial, sans-serif

//Compiles to:
body {
  font: 14px Arial, sans-serif;
}

font-size = 14px

body
  font font-size Arial, sans-serif

//Compiles to:
body {
  font: 14px Arial, sans-serif;
}

Variables can even consist of an expression list:

font-size = 14px
font-stack = "Lucida Grande", Arial, sans-serif

body
  font font-size font-stack

//Compiles to:
body {
  font: 14px "Lucida Grande", Arial, sans-serif;
}

font-size = 14px
font-stack = "Lucida Grande", Arial, sans-serif

body
  font font-size font-stack

//Compiles to:
body {
  font: 14px "Lucida Grande", Arial, sans-serif;
}

Identifiers (variable names, functions, etc.) may also include the $ character. For example:

$font-size = 14px
body {
  font: $font-size sans-serif;
}

$font-size = 14px
body {
  font: $font-size sans-serif;
}

We can not use null to create empty variable, but parentheses () can do that:

empty = ()
body {
  font: empty sans-serif;
}

empty = ()
body {
  font: empty sans-serif;
}

Compiles to:

    body {
      font: sans-serif;
    }

    body {
      font: sans-serif;
    }

Property Lookup

Another cool feature unique to Stylus is the ability to reference properties defined without assigning their values to variables. A great example of this is the logic required for vertically and horizontally center an element (typically done using percentages and negative margins, as follows):

#logo
  position: absolute
  top: 50%
  left: 50%
  width: w = 150px
  height: h = 80px
  margin-left: -(w / 2)
  margin-top: -(h / 2)

#logo
  position: absolute
  top: 50%
  left: 50%
  width: w = 150px
  height: h = 80px
  margin-left: -(w / 2)
  margin-top: -(h / 2)

Instead of assigning the variables w and h, we can simply prepend the @ character to the property name to access the value:

#logo
  position: absolute
  top: 50%
  left: 50%
  width: 150px
  height: 80px
  margin-left: -(@width / 2)
  margin-top: -(@height / 2)

#logo
  position: absolute
  top: 50%
  left: 50%
  width: 150px
  height: 80px
  margin-left: -(@width / 2)
  margin-top: -(@height / 2)

Another use-case is conditionally defining properties within mixins based on the existence of others . In the following example, we apply a default z-index of 1—but only if z-index was not previously specified:

position()
  position: arguments
  z-index: 1 unless @z-index

#logo
  z-index: 20
  position: absolute

#logo2
  position: absolute

position()
  position: arguments
  z-index: 1 unless @z-index

#logo
  z-index: 20
  position: absolute

#logo2
  position: absolute

Property lookup will "bubble up" the stack until found, or return null if the property cannot be resolved. In the following example, @color will resolve to blue:

body
  color: red
  ul
    li
      color: blue
      a
        background-color: @color

body
  color: red
  ul
    li
      color: blue
      a
        background-color: @color

Variables #

Property Lookup #

Variables

Property Lookup