zotero/scss/components/_item-tree.scss

#zotero-items-pane {
  min-width: 290px;
  min-height: 150px;
  height: 150px;
  width: 290px;
}

#zotero-items-tree {
  .virtualized-table-header .icon {
	width: 13px;
	height: 13px;
  }

  .cell.primary {
	.retracted {
	  width: 12px;
	  margin-inline-start: 3px;
	}

	.tag-swatch {
	  display: inline-block;
	  min-width: .728em;
	  min-height: .728em;
	  margin-inline-start: 3px;
	  border-radius: .15em;
	}
  }

  .cell.hasAttachment {
	box-sizing: content-box;
	padding: 0 4px;
  }

  .cell.numNotes {
	text-align: center;
  }
}