Чит-подсказка к финальному испытанию.

.palette-small {
    counter-reset: cnt;    
}

.palette-small div[class*="color"]:before {
    counter-increment: cnt;
    content: counter(cnt);
}


.part,
.palette-small {
    display: flex;
}

/*=====================Первая============================*/

.palette-box:first-of-type .palette-small {
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.palette-box:first-of-type .palette-small .color-2,
.palette-box:first-of-type .palette-small .color-5 {
    align-self: stretch;   
}

.palette-box:first-of-type .palette-small .color-2 {order: 1;}

.palette-box:first-of-type .palette-small .color-4 {order: 2;}

/*=====================Вторая============================*/

.palette-box:nth-of-type(2) .palette-small {
    flex-direction: column-reverse;
    justify-content: space-between;
    
}

.palette-box:nth-of-type(2) .palette-small .color-2,
.palette-box:nth-of-type(2) .palette-small .color-6{
    align-self: flex-end;   
}

.palette-box:nth-of-type(2) .palette-small .color-1,
.palette-box:nth-of-type(2) .palette-small .color-4 {
    align-self: flex-start;   
}

/*======================Третья===========================*/

.palette-box:nth-of-type(3) .palette-small {
    justify-content: space-between;
}

.palette-box:nth-of-type(3) .palette-small .part {
    display: flex;    
    flex-direction: column;
    justify-content: space-between;
}

/*======================Четвертая===========================*/

.palette-box:nth-of-type(4) .palette-small {
    justify-content: space-between;    
}

.palette-box:nth-of-type(4) .palette-small .part:first-of-type{
    display: flex;    
}

.palette-box:nth-of-type(4) .palette-small .part:last-of-type{
    display: flex;  
    flex-direction: column-reverse;
    justify-content: space-between;
}