jupyterlab/packages/debugger/style/icons.css

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

button.jp-Button.bp3-button.bp3-minimal.jp-TreeView.jp-TreeView,
button.jp-Button.bp3-button.bp3-minimal.jp-TreeView.jp-TableView {
  display: flex;
  align-items: center;
  -webkit-transition: 0.4s;
  transition: 0.4s;
  width: 35px;
}

button.jp-Button.bp3-button.bp3-minimal.jp-TreeView:hover {
  cursor: pointer;
  background-color: var(--jp-layout-color1);
}

button.jp-Button.bp3-button.bp3-minimal.jp-TableView:hover {
  cursor: pointer;
  background-color: var(--jp-layout-color1);
}

.jp-ViewModeSelected {
  background-color: var(--jp-layout-color1);
}