div {
    display: none;
}

@media screen and (max-width: 400px) {
    .aa {display: block;}
}

@media screen and (min-width: 301px) and (max-width: 600px) {
    .bb {display: block;}
}

@media screen and (min-width: 601px) {
    .cc {display: block;}
}


@media screen and (min-width: 961px) {
    .dd {display: block;}
}