Fixed observatory header buttons font

runtime/observatory/lib/src/elements/css/shared.css

Index: runtime/observatory/lib/src/elements/css/shared.css
diff --git a/runtime/observatory/lib/src/elements/css/shared.css b/runtime/observatory/lib/src/elements/css/shared.css
index f9b4a6139664d38f01773a29980e7d52c8ffec51..a914e8792e1dcfc8f2ad7239997146ebc07cf566 100644
--- a/runtime/observatory/lib/src/elements/css/shared.css
+++ b/runtime/observatory/lib/src/elements/css/shared.css
@@ -11,6 +11,10 @@ body {
   font: 400 14px 'Montserrat', sans-serif;
 }
 
+button {
+  font: 400 14px 'Montserrat', sans-serif;
+}
+
 .content {
   padding-left: 10%;
   font: 400 14px 'Montserrat', sans-serif;