userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to XUL */

/* URLバーのIMEをOFFに */
#urlbar *|input {
  ime-mode: inactive !important;
}

/* MacでもFaviconを表示 */
.bookmark-item[image] .toolbarbutton-icon {
  padding: 0 !important;
  margin:0 4px 0px -3px !important;
  width: 16px !important;
  height: 16px !important;
  display: inline !important;
}
.bookmark-item[image] .toolbarbutton-text-stack {
  display: none !important;
}
.bookmark-item[image]:hover {
  background: url("chrome://global/skin/toolbar/toolbarbutton-customhover-mid.png") !important;
  -moz-border-radius: 8px !important;
}
.bookmark-item[image]:hover:active {
  background: url("chrome://browser/skin/bookmark-open-mid.png") !important;
}