misc: add spectral font (for dsfr) (#62259)

README

@@ -343,6 +343,14 @@ copyright notices:
   #
   # TODO: update once the DSFR team gets back to it.
 
+* Spectral
+  # Copyright 2017 Production Type (info@productiontype.com)
+  #
+  # This Font Software is licensed under the SIL Open Font License, Version 1.1.
+  #
+  # https://www.fontsquirrel.com/license/spectral
+
+
 ~~~~
 
 Some theme variant files have their own specific licenses; refer to

static/includes/fonts/_spectral.scss

@@ -0,0 +1,12 @@
+@mixin spectral-font($type, $weight) {
+	@font-face {
+		font-family: 'Spectral';
+		src: url('/static/fonts/Spectral/Spectral-#{$type}.woff2') format('woff2'),
+		     url('/static/fonts/Spectral/Spectral-#{$type}.woff') format('woff');
+		font-weight: $weight;
+		font-style: normal;
+	}
+}
+
+@include spectral-font('Regular', 400);
+@include spectral-font('ExtraBold', 800);