*{
    box-sizing: border-box;
}

body{
    background-color: aquamarine;
}

#padre{
    width: 90%;
    height: 300px;
    margin: 10px auto;
    background-color: blue;
    padding: 16px;
    display: flex;
    justify-content: space-between;
}

#hijo1{
    width: 20%;
    height: 268px;
    background-color: brown;
}

#hijo2{
    width: 80%;
    height: 268px;
    background-color: rgb(226, 12, 12);
    padding: 16px;
    margin-left: 16px;
}

#nieto1{
    width: 100%;
    height: 236px;
    background-color: rgb(255, 230, 0);
}