fonts: add Inter (#65120)

README

@@ -368,6 +368,14 @@ copyright notices:
   #
   # https://www.fontsquirrel.com/license/playfair-display
 
+* Inter
+  # Copyright (c) 2016-2020 The Inter Project Authors.
+  # "Inter" is trademark of Rasmus Andersson.
+  #
+  # This Font Software is licensed under the SIL Open Font License, Version 1.1.
+  #
+  # https://github.com/rsms/inter
+
 ~~~~
 
 Some theme variant files have their own specific licenses; refer to

static/includes/fonts/_inter.scss

@@ -0,0 +1,24 @@
+@mixin inter-font($type, $weight, $style) {
+	@font-face {
+		font-family: 'Inter';
+		src: url('/static/fonts/Inter/Inter-#{$type}.woff2') format('woff2'),
+		     url('/static/fonts/Inter/Inter-#{$type}.woff') format('woff');
+		font-weight: $weight;
+		font-style: $style;
+	}
+}
+
+@mixin inter-font-pair($type, $weight) {
+	@include inter-font($type, $weight, normal);
+	@include inter-font('#{$type}Italic', $weight, italic);
+}
+
+@include inter-font-pair('Thin', 100);
+@include inter-font-pair('ExtraLight', 200);
+@include inter-font-pair('Light', 300);
+@include inter-font-pair('Regular', 400);
+@include inter-font-pair('Medium', 500);
+@include inter-font-pair('SemiBold', 600);
+@include inter-font-pair('Bold', 700);
+@include inter-font-pair('ExtraBold', 800);
+@include inter-font-pair('Black', 900);