Update css

src/application/dockpanel.css

@@ -13,7 +13,7 @@
 |----------------------------------------------------------------------------*/
 
 
-.p-DockPanel-tabPanel > .p-StackedPanel {
+.p-DockPanel-widget {
   background:var(--jp-layout-color1);
   border-left: var(--jp-border-width) solid var(--jp-border-color1);
   border-right: var(--jp-border-width) solid var(--jp-border-color1);

src/application/tabs.css

@@ -253,7 +253,7 @@
 |----------------------------------------------------------------------------*/
 
 
-.p-DockPanel-tabPanel > .p-TabBar .p-TabBar-tab.jp-mod-current:before {
+.p-DockPanel-tabBar .p-TabBar-tab.jp-mod-current:before {
   position: absolute;
   top: calc(-1 * var(--jp-border-width));
   left: calc(-1 * var(--jp-border-width));