<div id="completar_compra" class="modal fade" tabindex="-1" role="dialog">
    <div class="modal-dialog">
        <div class="modal-content">
            <div class="modal-body ">
                <div class="alert alert-info alert-dismissable">
                    <strong>Desea Registrar la Garantia !</strong> <a href="#" class="alert-link"></a>
                </div>
                 <label for="comprobante">Abjuntar Comprobante ( PDF )</label>
                <input type="file" name="comprobante" id="comprobante">

                <div class="modal-footer">
                    <a type="button" class="btn btn-default" data-dismiss="modal">Cancelar</a>
                    <button class="btn btn-success" name="registrar" value="registrar" data-toggle="modal" type="submit"><i class=" icon-ok"></i> <strong>Aceptar</strong>
                </div>
            </div> <!-- /item-row -->
        </div><!-- /.modal-dialog -->
    </div> 
</div>
<style type="text/css">
input[type="file"]#comprobante {
 width: 0.1px;
 height: 0.1px;
 opacity: 0;
 overflow: hidden;
 position: absolute;
 z-index: -1;
 }

label[for="comprobante"] {
 font-size: 14px;
 font-weight: 600;
 color: #fff;
 background-color: #106BA0;
 display: inline-block;
 cursor: pointer;
 padding: 5px 40px ;
 width: fit-content;
 text-align: center;
 }
</style>