How to remove the edges in the bootstrap modal header

Good day, I'm working with laravel and bootstrap, right now I'm more focused on the design, the problem is that when creating the modal I see two white lines as if it were a margin, is there any way to remove them?

Code

<div class="modal fullscreen-modal fade" role="dialog" tabindex="-1" id="ventana1">
                    <div class="modal-dialog modal-lg " role="document">
                        <div class="modal-content">
                            <div class="modal-header">
                            <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                            <span class="glyphicon glyphicon-remove-circle" aria-hidden="true"></span>
                                </button>

                            </div>
                            <div class="modal-body">


    <div class="container">
        <div class="row">
            <div class="col-xs-12">

                <div class="row">
                    <div class="col-xs-12 col-md-12 col-lg-12" align="">
                        <div style="font-size: 48px; color: white;"></div>
                    </div>
                </div>
                <br>
                <div class="row">
                    <div class="col-xs-12 " align="center">
                    <h2 style="color: white;">Encuesta Hello Survey</h2></center>
                        <center style="color: white;">Ten Feedback directo de tus usuarios</center>
                    </div>
                </div>
                <br><br><br> 
            </div>
        </div>
    </div>

CSS

.modal-header{   
    min-height: 1px;
    padding: 0px;
    margin: 0px 0;
    margin-left: 0px auto;
    margin-right: 0px auto;
    margin-top: 0px auto;
    margin-bottom: 0px auto;
    background-image: url('img/FODNDO_PRODUCTO.png');
}

.modal-body {
   background-image: url('img/FODNDO_PRODUCTO.png');
}
.modal-backdrop {
   background-image: url('img/FODNDO_PRODUCTO.png');
}
.close {
    color: gray; 
    opacity: 1;
}

It's basically underlined in yellow (sorry for such a bad edit)