* {
    box-sizing:border-box;
}


.B{
    background-color: rgb(178, 33, 207);
    border: solid 2px rgb(0, 0, 0);
    height: 125px;

}

@media (min-width: 10px) and (max-width: 764px) {

            .B{
                height: 200px;
                background-color: rgb(43, 76, 226);
            }

        }

@media (min-width: 765px) and (max-width: 1199px) {

            .B{
                height: 200px;
                background-color: rgb(43, 137, 226);
            }

        }

@media (min-width: 1200px) and (max-width: 1325px) {

            .B{
                height: 200px;
                background-color: rgb(178, 33, 207);
            }

        }