#id_qtd_criancas[readonly] {
    background-color: #eee;
    cursor: not-allowed;
}

#id_qtd_adultos[readonly] {
    background-color: #eee;
    cursor: not-allowed;
}

#id_qtd_adolescentes[readonly] {
    background-color: #eee;
    cursor: not-allowed;
}