align div to center of screen

1.container {
2  display: flex;
3  justify-content: center;
4  align-items: center;
5}

1Admit it, you can never remeber how to center a div....

1div.the-center-div {
2	margin: 0 auto;
3}

1.class{
2position: realtive;
3text-align: center;
4top: 50%;
5transform:translateY(-50%);
6}

1.class {
2	text-align: center;
3}