fonts: add Titillium (#26956)

README

@@ -102,6 +102,15 @@ copyright notices:
   #
   # https://www.fontsquirrel.com/license/barlow
 
+* Titillium font
+  # Copyright (c) 2008-2010, Accademia di Belle Arti di Urbino
+  # (www.campivisivi.net|direzione@accademiadiurbino.it),
+  # with Reserved Font Name Titillium.
+  #
+  # This Font Software is licensed under the SIL Open Font License, Version 1.1.
+  #
+  # https://www.fontsquirrel.com/license/Titillium
+
 ~~~~
 
 Some theme variant files have their own specific licenses; refer to

static/includes/_font-titillium.scss

@@ -0,0 +1,20 @@
+@mixin titillium-font($type, $weight, $style) {
+	@font-face {
+		font-family: 'Titillium';
+		src: url('../fonts/Titillium/titillium-#{$type}-webfont.woff2') format('woff2'),
+		     url('../fonts/Titillium/titillium-#{$type}-webfont.woff') format('woff');
+		font-weight: $weight;
+		font-style: $style;
+	}
+}
+
+@mixin titillium-font-pair($type, $weight) {
+	@include titillium-font($type, $weight, normal);
+	@include titillium-font('#{$type}italic', $weight, italic);
+}
+
+@include titillium-font-pair('thin', 200);
+@include titillium-font-pair('light', 300);
+@include titillium-font-pair('regular', 400);
+@include titillium-font-pair('semibold', 600);
+@include titillium-font-pair('bold', 700);