`extra.js` dark mode fix (#17707)

Co-authored-by: UltralyticsAssistant <web@ultralytics.com>

docs/overrides/javascript/extra.js

@@ -1,24 +1,39 @@
-// Apply theme colors based on dark/light mode -------------------------------------------------------------------------
-  document.body.setAttribute('data-md-color-scheme', isDark ? 'slate' : 'default');
-  document.body.setAttribute('data-md-color-primary', isDark ? 'black' : 'indigo');
+// Apply theme colors based on dark/light mode
+const applyTheme = (isDark) => {
+  document.body.setAttribute(
+    "data-md-color-scheme",
+    isDark ? "slate" : "default",
+  );
+  document.body.setAttribute(
+    "data-md-color-primary",
+    isDark ? "black" : "indigo",
+  );
 };
 
 // Check and apply appropriate theme based on system/user preference
 const checkTheme = () => {
-  const palette = JSON.parse(localStorage.getItem('.__palette') || '{}');
-  if (palette.index === 0) {  // Auto mode is selected
-    applyTheme(window.matchMedia('(prefers-color-scheme: dark)').matches);
+  const palette = JSON.parse(localStorage.getItem(".__palette") || "{}");
+  if (palette.index === 0) {
+    // Auto mode is selected
+    applyTheme(window.matchMedia("(prefers-color-scheme: dark)").matches);
   }
 };
 
 // Watch for system theme changes
-window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', checkTheme);
+window
+  .matchMedia("(prefers-color-scheme: dark)")
+  .addEventListener("change", checkTheme);
 
 // Initialize theme handling on page load
-document.addEventListener('DOMContentLoaded', () => {
-  document.getElementById('__palette_1')?.addEventListener('change', e =>
-    e.target.checked && setTimeout(checkTheme)
-  );
+document.addEventListener("DOMContentLoaded", () => {
+  // Watch for theme toggle changes
+  document
+    .getElementById("__palette_1")
+    ?.addEventListener(
+      "change",
+      (e) => e.target.checked && setTimeout(checkTheme),
+    );
+  // Initial theme check
   checkTheme();
 });