nixos/system/bookmarks/stylesheet.css

div.outline-2,
div.outline-3,
div.outline-4 {
  width: 50%;
  display: flex;
  flex-wrap: wrap;
  flex-direction: row;
}

div.outline-2 {
  width: unset;
}

div.outline-text-2,
div.outline-text-3,
div.outline-text-4 {
  width: 100%;
}