make null format look nice by default

apps/advanced/backend/web/css/site.css

@@ -18,6 +18,11 @@ body {
   padding: 14px 24px;
 }
 
+.not-set {
+	color: #c55;
+	font-style: italic;
+}
+
 /* add sorting icons to gridview sort links */
 a.asc:after, a.desc:after {
     position: relative;

apps/advanced/frontend/web/css/site.css

@@ -18,6 +18,11 @@ body {
   padding: 14px 24px;
 }
 
+.not-set {
+	color: #c55;
+	font-style: italic;
+}
+
 /* add sorting icons to gridview sort links */
 a.asc:after, a.desc:after {
     position: relative;

apps/basic/web/css/site.css

@@ -19,6 +19,11 @@ body {
 	padding: 14px 24px;
 }
 
+.not-set {
+	color: #c55;
+	font-style: italic;
+}
+
 /* add sorting icons to gridview sort links */
 a.asc:after, a.desc:after {
     position: relative;

framework/yii/base/Formatter.php

@@ -40,7 +40,7 @@ class Formatter extends Component
 	 */
 	public $datetimeFormat = 'Y/m/d h:i:s A';
 	/**
-	 * @var string the text to be displayed when formatting a null. Defaults to '(not set)'.
+	 * @var string the text to be displayed when formatting a null. Defaults to '<span class="not-set">(not set)</span>'.
 	 */
 	public $nullDisplay;
 	/**
@@ -69,7 +69,7 @@ class Formatter extends Component
 			$this->booleanFormat = [Yii::t('yii', 'No'), Yii::t('yii', 'Yes')];
 		}
 		if ($this->nullDisplay === null) {
-			$this->nullDisplay = Yii::t('yii', '(not set)');
+			$this->nullDisplay = '<span class="not-set">' . Yii::t('yii', '(not set)') . '</span>';
 		}
 	}