*{
    box-sizing: border-box;
}

#padre{
    width: 100%;
    height: 250px;
    background-color: rgba(135, 85, 236, 0.711);
    display: flex;
    flex-wrap: nowrap;
    padding: 10px;
}

#hijo1{
    width: 18%;
    height: 230px;
    background-color: palegoldenrod;
}

#hijo2{
    width: 100%;
    height: 230px;
    background-color: tomato;
    margin: 0 10px;
}

#hijo3{
    width: 18%;
    height: 230px;
    background-color: palegreen;
}