Matching menu font size to notebook

src/default-theme/index.css

@@ -265,7 +265,7 @@ body {
   background: #FAFAFA;
   color: rgba(0, 0, 0, 0.87);
   border-bottom: 1px solid #DDDDDD;
-  font: 13px "Helvetica Neue", Helvetica, Arial, sans-serif;
+  font: 14px "Helvetica Neue", Helvetica, Arial, sans-serif;
 }