@jupyterlab/application/style/datagrid.css

JupyterLab - Application

/*-----------------------------------------------------------------------------
| Copyright (c) Jupyter Development Team.
| Distributed under the terms of the Modified BSD License.
|----------------------------------------------------------------------------*/

.lm-DataGrid {
  min-width: 64px;
  min-height: 64px;
  border: 1px solid #a0a0a0;
}

.lm-DataGrid-scrollCorner {
  background-color: #f0f0f0;
}

.lm-DataGrid-scrollCorner::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 1px;
  height: 1px;
  background-color: #a0a0a0;
}