.zambezi-grid-cell.simple-nested-expander-cell {
  font-size: 16px;
  font-family: monospace;
  white-space: pre;
  color: #555;
}

.zambezi-grid-cell.simple-nested-expander-cell.is-collapse:hover,
.zambezi-grid-cell.simple-nested-expander-cell.is-expand:hover {
  color: black;
}

.zambezi-grid-cell.simple-nested-expander-cell.is-expand:after {
  content: '➖';
}

.zambezi-grid-cell.simple-nested-expander-cell.is-collapse:after {
  content: '➕';
}