Demo: Add system-ui as first font-family value.

blueimp · blueimp · commit 555782bf28a1 · 2020-05-08T17:04:37.000+09:00
diff --git a/css/demo.css b/css/demo.css
@@ -13,8 +13,8 @@ body {
   max-width: 750px;
   margin: 0 auto;
   padding: 1em;
-  font-family: -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial,
-    sans-serif;
+  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue',
+    Arial, sans-serif;
   line-height: 1.4;
   background: #212121;
   color: #dedede;
