IMPROVEMENT: Page Default container type

app/_config/config.yml

@@ -10,6 +10,9 @@ SilverStripe\View\SSViewer:
     - '$public'
     - '$default'
 
+Page:
+  default_container_class: 'container'
+
 #SilverStripe\Admin\LeftAndMain:
 #  extra_requirements_javascript:
 #    - 'colymba/gridfield-bulk-editing-tools:client/dist/js/main.js'

app/src/Extensions/ElementRows.php

@@ -170,7 +170,7 @@ class ElementRows extends DataExtension
 
         $object = $object ? $object : $this->owner;
 
-        if(!$object->isRoot()){
+        if (!$object->isRoot()) {
             $size = $object->getField('Size');
             $max = $size ? $max / (self::colsNumber() / $size) : $max;
             $parent = $object->Parent()->getOwnerPage();
@@ -185,8 +185,8 @@ class ElementRows extends DataExtension
     {
         $db = Config::inst()->get(self::class, 'db');
         $sizes = $db['Size'];
-        $sizes = preg_replace('!Enum\("([0-9,]+)","([0-9]+)"\)!i','$1', $sizes);
-        $sizes = explode(',',$sizes);
+        $sizes = preg_replace('!Enum\("([0-9,]+)","([0-9]+)"\)!i', '$1', $sizes);
+        $sizes = explode(',', $sizes);
 
         return max($sizes);
     }
@@ -216,7 +216,7 @@ class ElementRows extends DataExtension
         $container_styles = array_keys(self::$container_styles);
 
         if (!$type && $this->isRoot()) {
-            $type = $container_styles[0];
+            $type = \Page::DefaultContainer();
         }
 
         return $type;

app/src/Pages/Page.php

@@ -9,6 +9,13 @@ use DNADesign\Elemental\Models\ElementContent;
 
 class Page extends SiteTree
 {
+    private static $default_container_class = 'container';
+
+    public static function DefaultContainer()
+    {
+        return self::config()->get('default_container_class');
+    }
+
     /*
      * Shows custom summary of the post, otherwise
      * Displays summary of the first content element