v5.0.0.beta.1

Added

• Added a contrast-switch mixin that switches between two colors based on the
  lightness of a another color. Great for building button styles.
• Added an $all-text-inputs-invalid variable to target the :invalid
  pseudo-class on all text-based inputs.
• The ellipsis mixin now takes a $display argument.
• Added a font stack for system fonts: $font-stack-system.
• Added a hide-visually mixin that hides an element visually while still
  allowing the content to be accessible to assistive technology,
  e.g. screen readers.
• The font-face mixin now allows additional CSS properties to be included in
  its block, which will output as part of the @font-face declaration.
  See 2356719.

Changed

• The global default for the modular-scale ratio is now set to
  $major-third (1.25), instead of $perfect-fourth (1.333).
• All font stack variables are now prefixed with $font-stack-,
  e.g. $font-stack-helvetica.
• Global settings are now set via a $bourbon map, instead of variables.
  See 4e43c2d.
• The clearfix mixin now uses block display, instead of table.

Removed

• The $weight and $style arguments in the font-face mixin have been
  deprecated. 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.

Full Changelog