How can I change the check box option when its stored in api?

The checkbox is stored as div.

<div class="container">
    </div>

And in js it is stored as array.

var jqxhr = $.get("https://supercardsbrowserextensiondemo.azurewebsites.net/api/category/tree", function(data) {
            let tree = new Tree('.container', {
                data: data,
                closeDepth: 2,
                loaded: function() {
                    /*.values = ['0-0-0', '0-1-1'];
                    console.log(this.selectedNodes)
                    console.log(this.values)
                    this.disables = ['0-0-0', '0-0-1', '0-0-2']*/
                },
                onChange: function() {
                    console.log(this.values);
                }
            });

I want to change the checkbox and add some styling. Is there any way to apply some css??

It currently looks like this. It is just displaying the whole thing. There is no checkbox input or label.