Fix Tor Browser falling back to a serif font for NoScript UI.

src/ui/common.css

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2023 Giorgio Maone <https://maone.net>
+ * Copyright (C) 2005-2024 Giorgio Maone <https://maone.net>
  *
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
@@ -12,6 +12,11 @@ body {
   font-family: system-ui, sans-serif;
 }
 
+html.tor:not(.mobile) > body {
+  /* Tor Browser may fallback to a serif system-ui font, which is ugly */
+  font-family: sans-serif;
+}
+
 html.mobile > body {
   font-family: Inter, sans-serif;
   font-size: 4mm;