Somewhat complete SASS mixin for font-feature-settings.

README.md

Pass any valid comma separated list of feature tag–value pairs, always in the form of "tag" value where value is 0 or 1. These will be mixed in with the defaults (as in $font-feature-defaults).

normalize-opentype-with-mixin.scss

@mixin font-feature-settings($feature-tag-value...) {

	$font-feature-defaults: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0;
	$out: $font-feature-defaults;

	@if length($feature-tag-value) > 0 {
		@each $pair in $feature-tag-value {
			$tag: nth($pair, 1);
			$nth: index($font-feature-defaults, $tag 0) or index($font-feature-defaults, $tag 1);
			@if type-of($nth) == number {
				$step: ();
				@if $nth > 1 {
					@for $i from 1 through $nth - 1 {
						$step: append($step, nth($out, $i), comma);
					}
				}
				$step: append($step, $pair, comma);
				@if $nth < length($out) {
					@for $i from $nth + 1 through length($out) {
						$step: append($step, nth($out, $i), comma);
					}
				}
				$out: $step;
			}
			@else {
				$out: append($out, $pair);
			}
		}
	}

	-webkit-font-feature-settings: $out;
	-moz-font-feature-settings: $out;
	font-feature-settings: $out;

}

html, body {
	@include font-feature-settings("dlig" 0);
}

h1, h2, h3 {
	@include font-feature-settings("dlig" 1);
}

abbr {
	text-transform: uppercase;
	@include font-feature-settings("smcp" 1, "c2sc" 1);
}

time {
	@include font-feature-settings();
}

pre, kbd, samp, code {
	@include font-feature-settings("kern" 0, "liga" 0, "dlig" 0, "pnum" 0, "tnum" 1, "onum" 0, "lnum" 1, "zero" 1);
}

normalize-opentype.css

html, body {
  -webkit-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 0;
  -moz-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 0;
  font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 0; }

h1, h2, h3 {
  -webkit-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 1;
  -moz-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 1;
  font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 1; }

abbr {
  text-transform: uppercase;
  -webkit-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "smcp" 1, "c2sc" 1;
  -moz-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "smcp" 1, "c2sc" 1;
  font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "smcp" 1, "c2sc" 1; }

time {
  -webkit-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0;
  -moz-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0;
  font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0; }

pre, kbd, samp, code {
  -webkit-font-feature-settings: "kern" 0, "liga" 0, "pnum" 0, "tnum" 1, "onum" 0, "lnum" 1, "dlig" 0, "zero" 1;
  -moz-font-feature-settings: "kern" 0, "liga" 0, "pnum" 0, "tnum" 1, "onum" 0, "lnum" 1, "dlig" 0, "zero" 1;
  font-feature-settings: "kern" 0, "liga" 0, "pnum" 0, "tnum" 1, "onum" 0, "lnum" 1, "dlig" 0, "zero" 1; }