enforce disabled system + prefixed colors

user.js

@@ -1186,6 +1186,9 @@ user_pref("pdfjs.disabled", false); // [DEFAULT: false]
 /* 2621: disable links launching Windows Store on Windows 8/8.1/10 [WINDOWS]
  * [1] https://www.ghacks.net/2016/03/25/block-firefox-chrome-windows-store/ ***/
 user_pref("network.protocol-handler.external.ms-windows-store", false);
+/* 2622: enforce no system colors; they can be fingerprinted
+ * [SETTING] General>Language and Appearance>Fonts and Colors>Colors>Use system colors ***/
+user_pref("browser.display.use_system_colors", false); // [DEFAULT: false]
 
 /** DOWNLOADS ***/
 /* 2650: discourage downloading to desktop