Add padding between layout columns.

modules/ui/dashboard/css/dashboard_layout.css

@@ -0,0 +1,7 @@
+.layout--twocol .layout__region {
+  box-sizing: border-box;
+}
+
+.layout--twocol .layout__region--first {
+  padding-right: 1.5em;
+}

modules/ui/dashboard/farm_ui_dashboard.libraries.yml

@@ -0,0 +1,4 @@
+dashboard_layout:
+  css:
+    theme:
+      css/dashboard_layout.css: { }

modules/ui/dashboard/src/Controller/DashboardController.php

@@ -164,7 +164,11 @@ class DashboardController extends ControllerBase {
     }
 
     // Build the layout.
-    return $layoutInstance->build($regions);
+    $render = $layoutInstance->build($regions);
+
+    // Add the dashboard_layout styles.
+    $render['#attached']['library'][] = 'farm_ui_dashboard/dashboard_layout';
+    return $render;
   }
 
 }