.tabbrowser-tabs {
  background-color: #525252 !important;
}

#TabsToolbar .tabbrowser-tab {
    -moz-border-top-colors: none !important;
    -moz-border-left-colors: none !important;
    -moz-border-right-colors: none !important;
    -moz-border-bottom-colors: none !important;
    border-color: #000000 !important;
    border-style:  solid !important;
    border-width: 1px 0px 0px 0px !important;
    text-shadow: 0 0 4px rgba(80,80,80,.2) !important;
    border-radius: 0px !important;
}