Flexbox 1, "Сложные палитры" 100%

.palette-small {
display: flex;
}
/1 square/
.palette-box:first-child .palette-small {
flex-direction: column-reverse;
justify-content: center;
}
.palette-box:first-child .color-3 {
align-self: center;
order: 1;
}
.palette-box:first-child .color-4 {
align-self: center;
order: -1;
}
/2 square/
.palette-box:nth-child(2) .palette-small {
flex-direction: column-reverse;
justify-content: space-between;
}
.palette-box:nth-child(2) .color-1,
.palette-box:nth-child(2) .color-4 {
align-self: flex-start;
}

.palette-box:nth-child(2) .color-2,
.palette-box:nth-child(2) .color-6 {
align-self: flex-end;
}
/3 square/
.palette-box:nth-child(3) .palette-small {
flex-direction: row;
justify-content: space-between;
}
.palette-box .part {
display: flex;
}
.palette-box:nth-child(3) .part {
flex-direction: column;
justify-content: space-between;
}
/4 square/
.palette-box:last-child .palette-small {
justify-content: space-between;
}
.palette-box:last-child .part:last-child {
flex-direction: column-reverse;
justify-content: space-between;
}