css flexboxで最後,最初だけ逆端寄せ#

最初だけ左寄せ#

.f_box{
    display: flex;
    justify-content: flex-end;
}
.f_item:first-child{
    margin-right: auto;
}

.f_box{
    display: flex;
}
.f_item:last-child{
    margin-left: auto;
}