center without flex code example

Example 1: flex force div right side

.parent {
  display: flex;
}
.child {
  margin-left: auto;
  order: 2;
}

Example 2: flex block reponsive

/* big screen */
.navigation {
	display: flex;
	flex-flow: row wrap;
	/* Aligne les items à end line sur main-axis */
	justify-content: flex-end;
}

/* medium  screen */
@media all and (max-width: 800px) {
	.navigation {
	/* on centre en répartissant l'espace entre les items */
	justify-content: space-around;
	}
}

/* little screen */
@media all and (max-width: 500px) {
	.navigation {
	/* On n'utilise plus row mais column */
	flex-direction: column;
	}
}