_mixin_linear-gradient.scss

@mixin linear-gradient($angle, $color1, $offset1, $color2 ,$offset2:100, $color3:null, $offset3:100, $color4:null, $offset4:100, $color5:null, $offset5:100){
    $angle_webkit:'left top, left bottom';
    $angle_svg:'%20x2%3d%220%25%22%20y2%3d%22100%25%22';
    $color-stop1_svg:'%3cstop%20style%3d%22stop%2dcolor%3a%23'#{$color1}'%22%20offset%3d%22'#{$offset1}'%25%22%2f%3e';
    $color-stop2_svg:'%3cstop%20style%3d%22stop%2dcolor%3a%23'#{$color2}'%22%20offset%3d%22'#{$offset2}'%25%22%2f%3e';
    $color-stop3_svg:'';
    $color-stop4_svg:'';
    $color-stop5_svg:'';
    @if $angle == right{
        $angle_svg:'%20x2%3d%22100%25%22';
    }
    @if $angle == bottom{
        $angle_svg:'%20x2%3d%220%22%20y1%3d%22100%25%22';
    }
    @if $angle == left{
        $angle_svg:'';
    }
    @if $color3 != null {
        $color-stop3_svg:'%3cstop%20style%3d%22stop%2dcolor%3a%23'#{$color3}'%22%20offset%3d%22'#{$offset3}'%25%22%2f%3e';
    }
    @if $color4 != null {
        $color-stop4_svg:'%3cstop%20style%3d%22stop%2dcolor%3a%23'#{$color4}'%22%20offset%3d%22'#{$offset4}'%25%22%2f%3e';
    }
    @if $color5 != null {
        $color-stop5_svg:'%3cstop%20style%3d%22stop%2dcolor%3a%23'#{$color5}'%22%20offset%3d%22'#{$offset5}'%25%22%2f%3e';
    } 
    background-image:url(data:image/svg+xml,%3c%3fxml%20version%3d%221%2e0%22%3f%3e%3csvg%20xmlns%3d%22http%3a%2f%2fwww%2ew3%2eorg%2f2000%2fsvg%22%20width%3d%22100%25%22%20height%3d%22100%25%22%3e%3cdefs%3e%3clinearGradient%20id%3d%22G%22#{$angle_svg}%3e#{$color-stop1_svg}#{$color-stop2_svg}#{$color-stop3_svg}#{$color-stop4_svg}#{$color-stop5_svg}%3c%2flinearGradient%3e%3c%2fdefs%3e%3crect%20width%3d%22100%25%22%20height%3d%22100%25%22%20fill%3d%22url%28%23G%29%22%2f%3e%3c%2fsvg%3e);
}

style.css

  background-image: url(data:image/svg+xml,%3c%3fxml%20version%3d%221%2e0%22%3f%3e%3csvg%20xmlns%3d%22http%3a%2f%2fwww%2ew3%2eorg%2f2000%2fsvg%22%20width%3d%22100%25%22%20height%3d%22100%25%22%3e%3cdefs%3e%3clinearGradient%20id%3d%22G%22%20x2%3d%220%25%22%20y2%3d%22100%25%22%3e%3cstop%20stop%2dcolor%3d%22#bce13d%22%20offset%3d%220%%22%2f%3e%3cstop%20stop%2dcolor%3d%22#f7fee7%22%20offset%3d%2250%%22%2f%3e%3cstop%20stop%2dcolor%3d%22black%22%20offset%3d%22100%%22%2f%3e%3c%2flinearGradient%3e%3c%2fdefs%3e%3crect%20width%3d%22100%25%22%20height%3d%22100%25%22%20fill%3d%22url%28%23G%29%22%2f%3e%3c%2fsvg%3e);
  background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #bce13d)color-stop(0%, #bce13d)color-stop(100%, black));
  background-image: -webkit-linear-gradient(top, #bce13d 0%,#f7fee7 50%,black 100%);
  background-image: -moz-linear-gradient(top, #bce13d 0%,#f7fee7 50%,black 100%);
  background-image: -ms-linear-gradient(top, #bce13d 0%,#f7fee7 50%,black 100%);
  background-image: -o-linear-gradient(top, #bce13d 0%,#f7fee7 50%,black 100%);
  background-image: linear-gradient(top, #bce13d 0%,#f7fee7 50%,black 100%); }

style.scss

@import "_mixin_linear-gradient.scss";
.selector{
  //引数は、<方向>,<色1>,<位置1>,<色2>,<位置2>,<色3>,<位置3>...
  //色には＃は付けない。また、16進数のみ
  //offset にはパーセンテージで渡す。単位は付けない
  @include linear-gradient(top, "BCE13D", 0, "F7FEE7", 50, "000000", 100);
}

SVGのみ抜粋。