Starting from the KoolReport 1.27.6, we can added client-side library like Bootstrap, jQuery to view very easy like below:

<?php
class MyReport extends \koolreport\KoolReport
{
    use \koolreport\clients\jQuery;
    use \koolreport\clients\Bootstrap;
    use \koolreport\clients\FontAwesome;
    
}

If you want to add only Bootstrap CSS, you can do:

<?php
class MyReport extends \koolreport\KoolReport
{
    use \koolreport\clients\BootstrapCSS;
    
}

Easy, isn't it?