xpi/content/css/win8/menubarextra.css
@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

@-moz-document url(chrome://browser/content/browser.xul) {

	#main-window:not([tabsintitlebar])[tabsontop='false'] #toolbar-menubar:not([inactive="true"]),
    #main-window:not([tabsintitlebar])[tabsontop='false'] #toolbar-menubar[autohide="false"] {
	  background: #f6f6f6 !important;
	  border-top: 1px solid hsla(209,67%,12%,0.35) !important;
	  border-bottom: 1px solid #e9f2fa !important;
	  background-clip: padding-box !important;
	  border-top-left-radius: 2px !important;
	  border-top-right-radius: 2px !important;
	  box-shadow: none !important;
	}
	#main-window:not([tabsintitlebar])[tabsontop='false'][sizemode="normal"] #toolbar-menubar:not([inactive="true"]),
    #main-window:not([tabsintitlebar])[tabsontop='false'][sizemode="normal"] #toolbar-menubar[autohide="false"] {
	  border-left: 1px solid hsla(209,67%,12%,0.35) !important;
	  border-right: 1px solid hsla(209,67%,12%,0.35) !important;
	}
  
    #main-window:not([tabsintitlebar])[tabsontop='false'] #toolbar-menubar:not([inactive="true"]) ~ * ~ #nav-bar,
	#main-window:not([tabsintitlebar])[tabsontop='false'] #toolbar-menubar[autohide="false"] ~ * ~ #nav-bar  {
	  border-top:0px !important;
	  border-top-left-radius: 0px !important;
	  border-top-right-radius: 0px !important;
	  box-shadow: none !important;
	}

	#main-window:not([tabsintitlebar])[tabsontop='false'] #main-menubar {
	  background:none !important;
	}

	#main-window[sizemode=normal]:not([tabsintitlebar])[tabsontop='false'] #navigator-toolbox #TabsToolbar {
      border-left: 1px solid hsla(209,67%,12%,0.35) !important;
      border-right: 1px solid hsla(209,67%,12%,0.35) !important;
      background-clip: padding-box !important;
	}
	
	
	@media (-moz-os-version: windows-win10) {
		
	  #main-window:not([tabsintitlebar])[tabsontop='false'] #toolbar-menubar:not([inactive="true"]),
      #main-window:not([tabsintitlebar])[tabsontop='false'] #toolbar-menubar[autohide="false"] {
	    border-top: 0 !important;
	    border-top-left-radius: 0 !important;
	    border-top-right-radius: 0 !important;
	  }
		
	  #main-window:not([tabsintitlebar])[tabsontop='false'][sizemode="normal"] #toolbar-menubar:not([inactive="true"]),
      #main-window:not([tabsintitlebar])[tabsontop='false'][sizemode="normal"] #toolbar-menubar[autohide="false"],
	  #main-window[sizemode=normal]:not([tabsintitlebar])[tabsontop='false'] #navigator-toolbox #TabsToolbar {
		border-left: 0 !important;
		border-right: 0 !important;
	  }

	}

}