/// Applies vendor prefixes to as many properties as it is given.
///
/// @param {Map} $declarations - Declarations to prefix. Pass a map of key:value
/// pairs.
/// @param {List} $prefixes [webkit moz ms o] - List of prefixes to use.
///
/// @output Each property with the chosen vendor prefixes as well as the
/// standard, non-prefixed declarations.
///
/// @group Utilities
@mixin prefix($declarations, $vendors: (webkit moz ms o)) {
  @each $property, $value in $declarations {
    @each $prefix in $prefixes {
      #{'-' + $prefix + '-' + $property}: $value;
    }

    #{$property}: $value;
  }
}