gecko/toolkit/themes/pinstripe/mozapps/handling/handling.css

#description-image:not([src]) {
  height: 32px;
  width: 32px;
}

richlistitem {
  min-height: 36px; /* Don't forget to update the richlistbox height! */
}

richlistbox {
  /* 3 items high, plus 4px for top and bottom margins, less 2px for border */
  min-height: 110px; 
}