import Montserrat font face (#27054)

https://www.fontsquirrel.com/fonts/montserrat

README

@@ -111,6 +111,14 @@ copyright notices:
   #
   # https://www.fontsquirrel.com/license/Titillium
 
+* Montserrat font
+  # Copyright 2011 The Montserrat Project Authors
+  # (https://github.com/JulietaUla/Montserrat)
+  #
+  # This Font Software is licensed under the SIL Open Font License, Version 1.1.
+  #
+  # https://www.fontsquirrel.com/license/montserrat
+
 ~~~~
 
 Some theme variant files have their own specific licenses; refer to

static/includes/_font-montserrat.scss

@@ -0,0 +1,20 @@
+@mixin montserrat-font($type, $weight, $style) {
+	@font-face {
+		font-family: 'Montserrat';
+		src: url('../fonts/Montserrat/montserrat-#{$type}-webfont.woff2') format('woff2'),
+		     url('../fonts/Montserrat/montserrat-#{$type}-webfont.woff') format('woff');
+		font-weight: $weight;
+		font-style: $style;
+	}
+}
+
+@mixin montserrat-font-pair($type, $weight) {
+	@include montserrat-font($type, $weight, normal);
+	@include montserrat-font('#{$type}italic', $weight, italic);
+}
+
+@include montserrat-font-pair('thin', 100);
+@include montserrat-font-pair('light', 300);
+@include montserrat-font-pair('regular', 400);
+@include montserrat-font-pair('semibold', 600);
+@include montserrat-font-pair('bold', 700);