Migrating from v4 to v5

Removal of prefixing features

The following features for prefixing CSS properties have been removed. We suggest consulting Can I Use to see if prefixes are needed for a property, and using Autoprefixer to add the prefixes based on your project’s browser support needs.

  • align-items
  • animation-delay
  • animation-direction
  • animation-duration
  • animation-fill-mode
  • animation-iteration-count
  • animation-name
  • animation-play-state
  • animation-timing-function
  • animation
  • appearance
  • backface-visibility
  • background-image
  • background
  • border-image
  • box-sizing
  • calc
  • column-count
  • column-fill
  • column-gap
  • column-rule-color
  • column-rule-style
  • column-rule-width
  • column-rule
  • column-span
  • column-width
  • columns
  • display
  • filter
  • flex-direction
  • flex
  • font-feature-settings
  • hidpi
  • hyphens
  • image-rendering
  • justify-content
  • keyframes
  • linear-gradient
  • perspective
  • placeholder
  • radial-gradient
  • selection
  • text-decoration-color
  • text-decoration-line
  • text-decoration-style
  • text-decoration
  • transform-origin
  • transform-style
  • transform
  • transition-delay
  • transition-duration
  • transition-property
  • transition-timing-function
  • transition
  • user-select


Bourbon’s global settings are no longer defined using individual variables (e.g. $asset-pipeline: true;) and are instead set within a map named $bourbon:

$bourbon: (
  "rails-asset-pipeline": true,

There are also a few changes and removals to settings:

  • The $global-prefixes setting has been removed now that most of the prefixing features have been removed and the prefixer mixin no longer uses it.
  • The $em-base settings variable has been removed now that the em and rem functions have been removed.
  • The $asset-pipeline setting is now rails-asset-pipeline in the $bourbon settings map.

em and rem

The em and rem functions have been removed (read the discussion on why). Use plain em and rem units, instead.


The position mixin no longer has default values for the $position and $coordinates arguments. Define values for those arguments each time you call the mixin.


The strip-units function is now strip-unit:

- $foo: strip-units(10px);
+ $foo: strip-unit(10px);


The size mixin now requires a comma-separated argument list:

- @include size(1em 2em);
+ @include size(1em, 2em);


The $weight and $style arguments in the font-face mixin have been removed. Instead, you can now include these—along with other CSS properties—within the mixin block and they’ll be output as part of the @font-face declaration:

- @include font-face(
-   "source-sans-pro",
-   "/fonts/source-sans-pro/source-sans-pro-regular",
-   400,
-   normal
- );
+ @include font-face(
+   "source-sans-pro",
+   "/fonts/source-sans-pro-regular"
+ ) {
+   font-style: normal;
+   font-weight: 400;
+ }


The triangle mixin no longer has default argument values. It also now requires two individual values to be set for its size:

- @include triangle(12px, #ccc, "up");
+ @include triangle("up", 12px, 6px, #ccc);

Font stack variables

All of the font stack variables are now prefixed with font-stack-. For example, $helvetica is now $font-stack-helvetica.

The $monospace variable has been removed and we now have variables for many monospace fonts:

Button variables

inputs has been removed from the names of the button variables:

  • $all-button-inputs is now $all-buttons.
  • $all-button-inputs-active is now $all-buttons-active.
  • $all-button-inputs-focus is now $all-buttons-focus.
  • $all-button-inputs-hover is now $all-buttons-hover.


The retina-image mixin has been removed. Use vanilla CSS, instead.

General removals

The following features that were deprecated in the v4 release cycle have now been removed:

  • button mixin
  • flex-grid function
    • Our focus on grid systems is now solely in Neat.
  • flex-gutter function
    • Our focus on grid systems is now solely in Neat.
  • golden-ratio function
    • This function simply wrapped the modular-scale function. Please use the modular-scale instead, e.g. modular-scale(1, 1em, $golden).
  • grid-width function
    • Our focus on grid systems is now solely in Neat.
  • inline-block mixin