div {
display: flex; 
justify-content: space-between;
}

.ligne1 {
background-color : pink;
}
.Box1 {
background : blue;	
width: 100px;
height: 100px;
}
.Box2 {
background : yellow;
width: 100px;
height: 100px;
}
.Box3 {
background : red;
width: 100px;
height: 100px;
}

.ligne2 {
background-color : pink;
display: flex;
justify-content: flex-end;
}
.L2Box1 {
background : green;	
width: 100px;
height: 100px;
}
.L2Box2 {
background : blue;
width: 100px;
height: 100px;
}
.L2Box3 {
background : purple;
width: 100px;
height: 100px;
}