///
/// Sass-mixin for CSS property `tab-size`, generates cross-browser-compatible
/// `tab-size` output.
///
/// @author drublic
///
/// @link http://caniuse.com/css3-tabsize caniuse
/// @link http://dev.w3.org/csswg/css-text/#tab-size1 spec
///
/// @param {Number} $value [4] - optional
///
/// @output
/// ```css
///  -moz-tab-size: <value>;
///       tab-size: <value>;
/// ```
///
/// @example
///  .selector {
///    @include x-tab-size(4);
///   }
///
@mixin x-tab-size ($value: 4) {
	-moz-tab-size: $value;
	     tab-size: $value;
}