Bug 1700023 - Make #detailsPane background transparent. r=desktop-theme-reviewers,Itiel

This will show the dialog background, which correctly adapts to Dark Mode.

Differential Revision: https://phabricator.services.mozilla.com/D109257

browser/themes/osx/places/organizer.css

@@ -145,7 +145,6 @@
 /* Info box */
 #detailsPane {
   border-top: 1px solid #919191;
-  background-color: #f0f0f0;
   padding: 10px;
 }