@jupyterlab/application/style/dockpanel.css

JupyterLab - Application

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

/*-----------------------------------------------------------------------------
| Variables
|----------------------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
| DockPanel
|----------------------------------------------------------------------------*/

.lm-DockPanel-widget,
.lm-TabPanel-stackedPanel {
  background: var(--jp-layout-color0);
  border-left: var(--jp-border-width) solid var(--jp-border-color1);
  border-right: var(--jp-border-width) solid var(--jp-border-color1);
  border-bottom: var(--jp-border-width) solid var(--jp-border-color1);
}

.lm-DockPanel-overlay {
  background: rgba(33, 150, 243, 0.1);
  border: var(--jp-border-width) dashed var(--jp-brand-color1);
  transition-property: top, left, right, bottom;
  transition-duration: 150ms;
  transition-timing-function: ease;
}

.lm-DockPanel-overlay.lm-mod-root-top,
.lm-DockPanel-overlay.lm-mod-root-left,
.lm-DockPanel-overlay.lm-mod-root-right,
.lm-DockPanel-overlay.lm-mod-root-bottom,
.lm-DockPanel-overlay.lm-mod-root-center {
  border-width: 2px;
}