.bg-cover {
    background-image: url('/img/layout//karwia/kategorie/karwia-nad-morzem-zdjecia.webp');
}
@media only screen and (max-width: 450px) {
    .bg-cover {
        background-image: url(/images/slider2.png);
        margin-bottom: 30px;
       
        position: relative;
        background-position: 0px 0px;
        background-size: 300%;
    }
}