#nav-bar {
    background-image: none !important;
}

.tabbrowser-tab,
.tabs-newtab-button {
    background: -moz-linear-gradient(hsla(0,0%,100%,.2), hsla(0,0%,25%,.2) 1px, hsla(0,0%,12%,.2) 50%) !important;
    background-position: -5px -2px !important;
    background-repeat: no-repeat !important;
    background-size: 200% !important;
}

.tabbrowser-tab[selected="true"] {
    background-image: -moz-linear-gradient(rgba(255,255,255,.3), rgba(255,255,255,.2) 2px, rgba(255,255,255,.1) 40%),-moz-linear-gradient(-moz-dialog, -moz-dialog) !important;
}