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

#main-window #cfx-tools-button {
-moz-image-region:rect(38px 28px 57px 0) !important;
}

#main-window #cfx-control-button {
-moz-image-region:rect(57px 28px 76px 0) !important;
}

}