PrestaShop 1.7中类型颜色形式的背景问题

I'm adding an type color "color picker" using helper forms in Ps 1.7, and by default is empty and the field background is background-color: rgb(0, 0, 0); added by inline so i can't understand where this comes from and i want to change it to different color when field is empty by default.

                array(
                    'type' => 'color',
                    'label' => $this->trans('example'),
                    'name' => 'example',
                    'hint' => $this->trans('example text.'),
                    'class' => 'text-center',
                ),

image example

You can set the value of the color picker in the tpl_vars e.g.

$helperForm->tpl_vars = array(
     'fields_value' => array(
         'nameofmycolorpicker' => '#3399ff',
     ),
);