Linear-Gradient mixin for Sass, part of YAML (https://github.com/yamlcss/yaml/blob/master/sass/yaml-sass/mixins/_yaml-mixins-core.scss)

SassMeister-input.scss

// ---
// Sass (v3.2.9)
// ---


// Linear Gradient with two colors for modern browsers without the corresponding IE-filter

// $direction ==> written in the standard-way: to bottom, to left ...
// $solid-color ==> replacement color for the one device that cannot show gradients or IE-filters
// $start-color ==> which color to start with
// $end-color ==> which color to end with

// $output ==> defines the output-type of the code
    // css3   ==> only CSS3-gradients
	// oldie  ==> only IE-filters for oldIE (versions before 9)
	// both   ==> both CSS3 and oldIE versions are printed

// As there is a default direction there is no use for a fourth if-case.

@mixin ym-linear-gradient($direction: "to bottom", $start-color: #eee, $end-color: #ccc, $output: both) {
	$old-direction: top;
	$very-old-direction:"left top, left bottom";
	$ie-direction: 0;

	@if $direction == "to right" {
		$very-old-direction: "left top, right top";
		$old-direction: left;
		$ie-direction: 1;
	}

	@if $output != "oldie" {
		background: -webkit-gradient(linear, #{$very-old-direction}, color-stop(0%,$start-color), color-stop(100%,$end-color));
		background:  -webkit-linear-gradient($old-direction, $start-color,$end-color);
		background: 	-moz-linear-gradient($old-direction, $start-color,$end-color);
		background: 	 -ms-linear-gradient($old-direction, $start-color,$end-color);
		background:    		 linear-gradient($direction, $start-color,$end-color);
	}

	@if $output != "css3" {
		$iecolor1: ie-hex-str($start-color);
		$iecolor2: ie-hex-str($end-color);
		filter: progid:DXImageTransform.Microsoft.Gradient(GradientType=#{$ie-direction}, startColorstr='#{$iecolor1}', endColorstr='#{$iecolor2}');
		zoom: 1;
	}
}


.test {
    @include ym-linear-gradient();
}

.test2 {
    @include ym-linear-gradient("to right", #a20000, #000 );
}

SassMeister-output.css

.test {
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #eeeeee), color-stop(100%, #cccccc));
  background: -webkit-linear-gradient(top, #eeeeee, #cccccc);
  background: -moz-linear-gradient(top, #eeeeee, #cccccc);
  background: -ms-linear-gradient(top, #eeeeee, #cccccc);
  background: linear-gradient("to bottom", #eeeeee, #cccccc);
  filter: progid:DXImageTransform.Microsoft.Gradient(GradientType=0, startColorstr='#FFEEEEEE', endColorstr='#FFCCCCCC');
  zoom: 1;
}

.test2 {
  background: -webkit-gradient(linear, left top, right top, color-stop(0%, #a20000), color-stop(100%, black));
  background: -webkit-linear-gradient(left, #a20000, black);
  background: -moz-linear-gradient(left, #a20000, black);
  background: -ms-linear-gradient(left, #a20000, black);
  background: linear-gradient("to right", #a20000, black);
  filter: progid:DXImageTransform.Microsoft.Gradient(GradientType=1, startColorstr='#FFA20000', endColorstr='#FF000000');
  zoom: 1;
}