I am new to yii2.. how to apply css to column, column heading of yii2 gridview??
<?php $gridColumns = [ ['class' => 'yii\grid\SerialColumn'], ['class' => 'yii\grid\CheckboxColumn'], 'name', 'company_mail', //change the color of heading 'no_employees', 'email:email', . . .]; echo GridView::widget([ 'dataProvider' => $dataProvider, 'filterModel' => $searchModel, 'columns' => $gridColumns, ]); ?> You can set particular column style/css using this way.
$columns = [ 'onenormalcolumn', 'anothercolumn', [ 'format'=>"ntext", // or other formatter 'attribute' => 'theattributeofmodel', 'contentOptions' => ['style' => 'width:50px'], // For TD 'headerOptions' => ['class' => 'ur-class'] // For TH ] ] You have to set your column in detailed mode:
<?php $columns = [ 'onenormalcolumn', 'anothercolumn', [ 'format'=>"ntext", // or other formatter 'attribute' => 'theattributeofmodel', 'options'=>[ 'style'=>'your rules here' ] ] ] ?> 
if you want change the column header css properties you should use headerOptions column propreties eg:
'columns' => [ ['class' => 'yii\grid\SerialColumn'], ....... 'anothercolumn', [ 'format'=>"ntext", // or other formatter 'attribute' => 'theattributeofmodel', 'headerOptions'=>[ 'style'=>'background-color:#ccf8fe' ] ], ], 