Update switcher button styles.

packages/settingeditor-extension/style/settingeditor.css

@@ -82,7 +82,6 @@
 
 
 #setting-editor .jp-PluginList-switcher {
-  background: red;
   height: var(--jp-private-settingeditor-switcher-height);
   position: absolute;
   top: 0;
@@ -91,6 +90,14 @@
 }
 
 
+#setting-editor .jp-PluginList-switcher button {
+  margin: 0;
+  padding: 0;
+  height: var(--jp-private-settingeditor-switcher-height);
+  width: 50%;
+}
+
+
 #setting-editor .jp-PluginList ul {
   background-color: var(--jp-layout-color1);
   color: var(--jp-ui-font-color1);