full width div in bootstrap 4

Why is my bottom border in the inside div not full width?

<div class="container-fluid">
        <div class="row">
            <div class="col-12 col-md-2 bg-light mh-100">
                <div class="d-flex justify-content-center border-bottom w-100">
                    <img class="my-3" src="img/img.png" alt="" srcset="" style="height:18px; width:110px;">
                </div>
            </div>
            <div class="col-12 col-md-10 bg-dark mh-100">
                <p>sfsdfsdfsd</p>
            </div>
        </div>
    </div>