@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

.tabs-newtab-button:-moz-system-metric(windows-compositor):not(:-moz-lwtheme) {
  list-style-image: url("chrome://browser/skin/tabbrowser/newtab-inverted.png") !important;
}

.tabs-newtab-button {
  width: 20px !important;
  background: none !important;
  border: none !important;
  border-top: none !important;
  border-left: none !important;
  border-right: none !important;
  padding-top: 5px !important;
}

.tabs-newtab-button:hover {
  background-image: -moz-linear-gradient(rgba(255,255,255,0), rgba(255,255,255,.5)),
                    -moz-linear-gradient(transparent, rgba(0,0,0,.25) 30%),
                    -moz-linear-gradient(transparent, rgba(0,0,0,.25) 30%) !important;
  background-position: 1px -1px, 0 -1px, 100% -1px !important;
  background-size: -moz-calc(100% - 2px) 100%, 1px 100%, 1px 100% !important;
  background-repeat: no-repeat !important;
}