.tabbrowser-tab
{
   margin-bottom: 2px !important;
   margin-right: 2px !important;
   -moz-border-radius-bottomleft:  6px !important;
   -moz-border-radius-bottomright: 6px !important;
}

.tabbrowser-tab:not([selected="true"])
{
   -moz-border-left-colors: rgba(255,255,240, 0.15) rgba(0, 0, 0, 0.0) !important;
}