BEM class names for filter-buttons

src/Forms/GridField/GridFieldFilterHeader.php

@@ -221,7 +221,7 @@ class GridFieldFilterHeader implements GridField_HTMLProvider, GridField_DataMan
                         ->setAttribute('title', _t('SilverStripe\\Forms\\GridField\\GridField.ResetFilter', "Reset"))
                         ->setAttribute('id', 'action_reset_' . $gridField->getModelClass() . '_' . $columnField)
                 );
-                $fields->addExtraClass('filter-buttons');
+                $fields->addExtraClass('grid-field__filter-buttons');
                 $fields->addExtraClass('no-change-track');
             }
 

templates/SilverStripe/Forms/GridField/GridFieldFilterHeader_Row.ss

@@ -1,5 +1,5 @@
-<% if Fields %>
-    <tr class="filter-header" style="display:none;">
+<% if $Fields %>
+    <tr class="grid-field__filter-header" style="display:none;">
 	   <% loop $Fields %>
 	       <th class="extra">$Field</th>
 	   <% end_loop %>