diff --git a/ButtonDropdown.php b/ButtonDropdown.php
index cb6fbb0..7b63b83 100644
--- a/ButtonDropdown.php
+++ b/ButtonDropdown.php
@@ -67,11 +67,11 @@ class ButtonDropdown extends Widget
      * @var boolean whether the label should be HTML-encoded.
      */
     public $encodeLabel = true;
-	/**
-	 * @var string name of a class to use for rendering dropdowns withing this widget. Defaults to [[Dropdown]].
-	 * @since 2.0.7
-	 */
-	public $dropdownClass = 'yii\bootstrap\Dropdown';
+    /**
+     * @var string name of a class to use for rendering dropdowns withing this widget. Defaults to [[Dropdown]].
+     * @since 2.0.7
+     */
+    public $dropdownClass = 'yii\bootstrap\Dropdown';
 
 
     /**
@@ -144,8 +144,8 @@ class ButtonDropdown extends Widget
         $config = $this->dropdown;
         $config['clientOptions'] = false;
         $config['view'] = $this->getView();
-		/** @var Widget $dropdownClass */
-		$dropdownClass = $this->dropdownClass;
-		return $dropdownClass::widget($config);
+        /** @var Widget $dropdownClass */
+        $dropdownClass = $this->dropdownClass;
+        return $dropdownClass::widget($config);
     }
 }
diff --git a/Nav.php b/Nav.php
index b50ad7f..947f604 100644
--- a/Nav.php
+++ b/Nav.php
@@ -107,9 +107,9 @@ class Nav extends Widget
     public $dropDownCaret;
     /**
      * @var string name of a class to use for rendering dropdowns withing this widget. Defaults to [[Dropdown]].
-	 * @since 2.0.7
+     * @since 2.0.7
      */
-	public $dropdownClass = 'yii\bootstrap\Dropdown';
+    public $dropdownClass = 'yii\bootstrap\Dropdown';
 
 
     /**
@@ -214,9 +214,9 @@ class Nav extends Widget
      */
     protected function renderDropdown($items, $parentItem)
     {
-		/** @var Widget $dropdownClass */
-		$dropdownClass = $this->dropdownClass;
-		return $dropdownClass::widget([
+        /** @var Widget $dropdownClass */
+        $dropdownClass = $this->dropdownClass;
+        return $dropdownClass::widget([
             'options' => ArrayHelper::getValue($parentItem, 'dropDownOptions', []),
             'items' => $items,
             'encodeLabels' => $this->encodeLabels,
diff --git a/Tabs.php b/Tabs.php
index 1cb7522..17fda2d 100644
--- a/Tabs.php
+++ b/Tabs.php
@@ -124,11 +124,11 @@ class Tabs extends Widget
      * @since 2.0.7
      */
     public $tabContentOptions = [];
-	/**
-	 * @var string name of a class to use for rendering dropdowns withing this widget. Defaults to [[Dropdown]].
-	 * @since 2.0.7
-	 */
-	public $dropdownClass = 'yii\bootstrap\Dropdown';
+    /**
+     * @var string name of a class to use for rendering dropdowns withing this widget. Defaults to [[Dropdown]].
+     * @since 2.0.7
+     */
+    public $dropdownClass = 'yii\bootstrap\Dropdown';
 
 
     /**
@@ -188,8 +188,8 @@ class Tabs extends Widget
                 if (!isset($linkOptions['data-toggle'])) {
                     $linkOptions['data-toggle'] = 'dropdown';
                 }
-				/** @var Widget $dropdownClass */
-				$dropdownClass = $this->dropdownClass;
+                /** @var Widget $dropdownClass */
+                $dropdownClass = $this->dropdownClass;
                 $header = Html::a($label, "#", $linkOptions) . "\n"
                     . $dropdownClass::widget(['items' => $item['items'], 'clientOptions' => false, 'view' => $this->getView()]);
             } else {
diff --git a/tests/TabsTest.php b/tests/TabsTest.php
index 867d6d9..f652843 100644
--- a/tests/TabsTest.php
+++ b/tests/TabsTest.php
@@ -199,7 +199,7 @@ class TabsTest extends TestCase
                 ],
                 [
                     'label' => 'Tab 2',
-                    'content' => 'some content'                            
+                    'content' => 'some content'
                 ],
                 [
                     'label' => 'Tab 3',
@@ -211,7 +211,7 @@ class TabsTest extends TestCase
                     'content' => 'some content'
                 ]
             ]
-        ]);        
+        ]);
         $this->assertContains('<li class="active"><a href="#mytab-tab2" data-toggle="tab">Tab 3</a></li>', $html);
     }
 }