.negrita{
    font-weight: bold;
}
#cuadro{
    width: 90%;
    margin-left: 5%;
}
#datos_a{
    text-align: center;
    width: 29%;
    float: left;
    margin-bottom: 90px;
    margin-top: 90px;
    margin-right: 2%;
    margin-left: 2%;
}