Merge pull request #4481 from jasongrout/toolbar-shadow

Add the boxshadow that we used to have on various toolbars to the main toolbar class

packages/apputils/style/toolbar.css

@@ -15,7 +15,10 @@
   display: flex;
   flex-direction: row;
   border-bottom: var(--jp-border-width) solid var(--jp-toolbar-border-color);
+  box-shadow: var(--jp-toolbar-box-shadow);
+  background: var(--jp-toolbar-background);
   min-height: var(--jp-toolbar-micro-height);
+  z-index: 1;
 }