can the background color in Bookmarks menu be changed from default grey
In an older version of FIreFox the Bookmarks menu had a light blue background. The latest version has a unpleasing yellowish grey. Is there away to get back to a light blue? I've tried thru "Customize" and was able to change my theme color, but not the Bookmarks menu background. Thank you.
Opaite Mbohovái (1)
I think you mean the "classic" Bookmarks menu on the menu bar, and not the newer style bookmarks menu which opens from the toolbar button (the one that looks like a bit like a clipboard and is joined to the star icon).
There is no built-in feature to change the background color of those menus, but you can do it using a custom style rule, or perhaps an add-on.
I realize the following is gibberish to most people, but it can be used to apply a new background color to the classic Bookmarks menu using either a userChrome.css file or the Stylish extension. If you don't find a more convenient method, a volunteer can give more details:
#bookmarksMenu menupopup .scrollbox-innerbox {
background-color: #dff !important;
}