diff --git a/system/bookmarks/darkmode.js b/system/bookmarks/darkmode.js
new file mode 100644
index 00000000..97f254f2
--- /dev/null
+++ b/system/bookmarks/darkmode.js
@@ -0,0 +1,15 @@
+// From https://www.geeksforgeeks.org/how-to-make-dark-mode-for-websites-using-html-css-javascript/
+// See also https://www.w3schools.com/howto/howto_js_toggle_dark_mode.asp
+function darkMode() {
+  let element = document.body;
+  let content = document.getElementById("DarkModetext");
+  element.className = "dark-mode";
+  content.innerText = "Dark Mode is ON";
+}
+
+function lightMode() {
+  let element = document.body;
+  let content = document.getElementById("DarkModetext");
+  element.className = "light-mode";
+  content.innerText = "Dark Mode is OFF";
+}