///
/// Generates appearance for a given element.
///
/// @author romamatusevich
///
/// @link http://caniuse.com/#feat=css-appearance caniuse
/// @link http://www.w3.org/TR/2004/CR-css3-ui-20040511/#appearance spec
/// @link https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-appearance MDN
/// @link http://css-tricks.com/almanac/properties/a/appearance css-tricks
///
/// @param {String} $value
///
/// @output
/// ```css
///   -webkit-appearance: <value>;
///      -moz-appearance: <value>;
///           appearance: <value>;
/// ```
///
/// @example
///   .selector {
///     @include x-appearance(button);
///   }
///
@mixin x-appearance ($value) {
	-webkit-appearance: $value;
	   -moz-appearance: $value;
	        appearance: $value;
}