kibana/x-pack/plugins/lens/public/editor_frame_service/editor_frame/data_panel_wrapper.scss

.lnsDataPanelWrapper {
  flex: 1 0 100%;
  overflow: hidden;
  background-color: lightOrDarkTheme($euiColorLightestShade, $euiColorInk);
}

.lnsDataPanelWrapper__switchSource {
  position: absolute;
  right: $euiSize + $euiSizeXS;
  top: $euiSize + $euiSizeXS;
}