align div content center

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

1/* this will center all children within the parent element. */
2.parent {
3  display: flex;
4  justify-content: center; /* horizontal */
5  align-items: center; /* vertical */
6}

1.center {
2  display: block;
3  margin-left: auto;
4  margin-right: auto;
5}

1.child {
2  ...
3  margin: 0 auto;
4}

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

1// example 1 
2div { display: grid; place-items: center; }
3
4// example 3
5div{ display:flex; align-items:center; }
6
7// example 3
8div { width: 100%; margin: 0 auto; }