@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

/* this style allows transparent toolbars, tabs bar & status bar */
/* tested on default theme only, firefox 3.0, Windows XP, Vista, Ubuntu 8.04 */

/* Toolbars, urlbar, searchbar and statusbar borderless */
   #urlbar, .searchbar-textbox, toolbox { border-style: none !important; }
    toolbar, #status-bar { border-style: none !important;
                           -moz-appearance: none !important; }

/* Transparency */
   #navigator-toolbox { -moz-appearance: none !important;
                        background-color: transparent !important; }
   #browser .plain { background-color: transparent !important; }
   #urlbar { -moz-appearance: none !important; }
   #urlbar:not([level="high"]):not([level="low"]) {
       background-color: transparent !important; }
   .searchbar-textbox { background-color: transparent !important;
                        -moz-appearance: none !important; }
   #status-bar { -moz-appearance: none !important;
                 background-color: transparent !important; }
   .tabbrowser-tabs { -moz-appearance: none !important;
                      background-color: transparent !important; }

/* wallpaper in background */

   #main-window[windowtype="navigator:browser"] {
       background-position: 0px 0 !important;
       -moz-appearance: none !important;
       background-repeat: no-repeat !important;
/*************************************************************************/
/* a wallpaper will eat RAM ressources so I advise you to compress it...

/* Here, I just put an example so you can see the result but I don't
   think using an image from web is a viable solution. You have 2 solutions:
   - use Data URI like both examples just below, but that's not recommanded
     because Stylish will freeze a little bit because of all these datas;
   - use userChrome.css: I think it's the best solution. Put your wallpaper
     in chrome directory of your profile and you just have to put this:
       #main-window[windowtype="navigator:browser"] {
           background-image: url("yourwallpaper.jpg") !important;}
   /*************************************************************************/

       background-image: url("http://www.enregistrersous.com/images/145679654120071022174003.jpg") !important;

   }


/* Background Image for toolbars & statusbar, more readable */

   #navigator-toolbox, #FindToolbar, .tabbrowser-tabs ,#status-bar {

/* choose your (transparent & clear) image thanks to Stylish > Insert > URI Data */
/* 400x25 is enough I think */

        background-image: url(
"data:image/png;base64,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"
        ) !important;
   }

/* Allows searchbar & urlbar readable */

   .searchbar-textbox, #urlbar:not([level="high"]):not([level="low"]) > 
     .autocomplete-textbox-container {

/* choose your (transparent & clear) image thanks to Stylish > Insert > URI Data */
/* 150x25 should be enough */

         background-image: url(
"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAJYAAAAZCAYAAADT59fvAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAgY0hSTQAAeiYAAICEAAD6AAAAgOgAAHUwAADqYAAAOpgAABdwnLpRPAAAABh0RVh0U29mdHdhcmUAUGFpbnQuTkVUIHYzLjMxN4N3hgAAAKNJREFUaEPt1rENxEAMA8Fzr+6/BR3sGrTZPPApA4Ia3zMz7/HTwHYD37D8dbC9gbMdKM9I/6+gIRhCsQHD8hRInkKGZViGVZAts3kKEItYxKJLo0vRK7GIRazismQ2ChKLWMSiS6NL0SuxiEWs4rJkNgoSi1jEokujS9ErsYhFrOKyZDYKEotYxKJLo0vRK7GIRazismQ2ChKLWMSiS6NL0esFdlOKNGiTRiQAAAAASUVORK5CYII="
         ) !important;
   }

/* chose Font color, don't forget to UNcomment -> 
   #main-window toolbarbutton { color: #FFFFFF !important; }
   #main-window toolbarbutton:hover { color:#000000 !important; }
   #status-bar { color: #0000FF !important; }

/* you can also change menubar font color
   but using icons instead of menu is better :P */