jupyterlab/packages/application-extension/style/base.css

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

#jp-MainLogo {
  width: calc(var(--jp-private-sidebar-tab-width) + var(--jp-border-width));
}

.jp-skiplink {
  position: absolute;
  top: -100em;
}

.jp-skiplink:focus-within {
  position: absolute;
  z-index: 10000;
  top: 0;
  left: 46%;
  margin: 0 auto;
  padding: 1em;
  width: 15%;
  box-shadow: var(--jp-elevation-z4);
  border-radius: 4px;
  background: var(--jp-layout-color0);
  text-align: center;
}

.jp-skiplink:focus-within a {
  text-decoration: underline;
  color: var(--jp-content-link-color);
}