#pagina {
    float: left;
    height: 650px;
    width: 99%;
    margin-left: 1%;

}


@media only screen and (max-width: 950px) {
    #pagina {
        margin-left: 3%;
        width: 95%;
    }
}

@media only screen and (max-width: 650px) {
    #pagina {
        float: none;
        width: 100%;
    }

}