gecko/toolkit/themes/winstripe/global/appPicker.css

#app-picker {
  width: 320px;
}

#content-description {
  font-weight: bold;
}

#content-icon,
.listcell-icon {
  margin: 5px;
  width: 32px;
  height: 32px;
}

.listcell-label {
  padding: 5px;
}