diff --git a/core/modules/layout/layout.admin.css b/core/modules/layout/layout.admin.css
index 05574d9..6e38bf4 100644
--- a/core/modules/layout/layout.admin.css
+++ b/core/modules/layout/layout.admin.css
@@ -3,24 +3,15 @@
 }
 
 .layout-region-demonstration {
+  background-image: -moz-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
+  background-image: -o-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
+  background-image: -ms-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
+  background-image: -webkit-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
+  background-image: -webkit-gradient(linear, left bottom, left top, color-stop(0.4, rgb(70,70,71)), color-stop(0.7, rgb(91,91,94)), color-stop(0.88, rgb(125,124,125)));
+  background-image: linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
   color: white;
+  font-size: 0.8em;
   margin: 3px;
   padding: 10px;
   text-transform: uppercase;
-  font-size: 0.8em;
-
-  background-image: linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
-  background-image: -o-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
-  background-image: -moz-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
-  background-image: -webkit-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
-  background-image: -ms-linear-gradient(bottom, rgb(70,70,71) 40%, rgb(91,91,94) 70%, rgb(125,124,125) 88%);
-
-  background-image: -webkit-gradient(
-    linear,
-    left bottom,
-    left top,
-    color-stop(0.4, rgb(70,70,71)),
-    color-stop(0.7, rgb(91,91,94)),
-    color-stop(0.88, rgb(125,124,125))
-  );
 }
diff --git a/core/modules/layout/layout.admin.inc b/core/modules/layout/layout.admin.inc
index 3ba2f78..b2bb8ad 100644
--- a/core/modules/layout/layout.admin.inc
+++ b/core/modules/layout/layout.admin.inc
@@ -6,7 +6,7 @@
  */
 
 /**
- * Page callback: Presents list of layouts.
+ * Page callback: Presents a list of layouts.
  *
  * @see layout_menu()
  */
@@ -43,7 +43,7 @@ function layout_page_list() {
 }
 
 /**
- * Page callback: Demonstrate a layout template.
+ * Page callback: Demonstrates a layout template.
  *
  * @see layout_menu()
  */
diff --git a/core/modules/layout/layout.module b/core/modules/layout/layout.module
index f4fb110..f35f5d5 100644
--- a/core/modules/layout/layout.module
+++ b/core/modules/layout/layout.module
@@ -29,7 +29,14 @@ function layout_menu() {
 }
 
 /**
- * Menu access callback. Check for layout existance.
+ * Access callback: Checks the existence of a layout.
+ *
+ * @param string $key
+ *   The key of the page layout being requested.
+ *
+ * @return
+ *   TRUE if the current user can access page layout menu items; FALSE
+ *   otherwise.
  */
 function layout_user_access($key) {
   return (user_access('administer layouts') && layout_manager()->getDefinition($key));
diff --git a/core/modules/layout/lib/Drupal/layout/Plugin/LayoutInterface.php b/core/modules/layout/lib/Drupal/layout/Plugin/LayoutInterface.php
index a835f23..829f3c2 100644
--- a/core/modules/layout/lib/Drupal/layout/Plugin/LayoutInterface.php
+++ b/core/modules/layout/lib/Drupal/layout/Plugin/LayoutInterface.php
@@ -28,11 +28,12 @@ public function getRegions();
   /**
    * Renders layout and returns the rendered markup.
    *
-   * @param boolean $admin
-   *   TRUE if the rendered layout is displayed in an administrative context,
-   *   FALSE otherwise.
+   * @param bool $admin
+   *   (optional) TRUE if the rendered layout is displayed in an administrative
+   *   context, FALSE otherwise. Defaults to FALSE.
    * @param array $regions
-   *   An array of region render arrays keyed by region machine names.
+   *   (optional) An array of region render arrays keyed by region machine
+   *   names. Defaults to array.
    *
    * @return string
    *   Rendered HTML output from the layout.
diff --git a/core/modules/layout/lib/Drupal/layout/Plugin/layout/layout/StaticLayout.php b/core/modules/layout/lib/Drupal/layout/Plugin/layout/layout/StaticLayout.php
index f3f6762..183fd01 100644
--- a/core/modules/layout/lib/Drupal/layout/Plugin/layout/layout/StaticLayout.php
+++ b/core/modules/layout/lib/Drupal/layout/Plugin/layout/layout/StaticLayout.php
@@ -87,7 +87,7 @@ public function renderLayout($admin = FALSE, $regions = array()) {
       '#content' => array(),
     );
 
-    // Render all regions needed for this layout.
+    // Renders all regions needed for this layout.
     foreach ($this->getRegions() as $region => $info) {
       // Initialize regions which were not provided as empty.
       $build['#content'][$region] = empty($regions[$region]) ? '' : $regions[$region];