#container1 {
    display: flex;
    min-height: 100vh;
    flex-direction: row;
    background-color: blueviolet;
}

#item1 {
    flex-grow: 1;
}
#item2 {
    flex-grow: 5;
}

#container2 {
    display:flex;
    flex-direction: column;
    background-color: burlywood;
    min-height: 100vh;
    justify-content: space-between;
}
#item3 {
    height: 20vh;
}
#item4 {
    min-height: 60vh;
}
#item7 {
    height: 20vh;
}

#container3 {
    display: flex;
    flex-direction: row;
    background-color: cornflowerblue;
    min-height: 60vh;
}

#item5 {
    flex-grow: 3;
}
#item6 {
    flex-grow: 1;
    background-color: crimson;
}