css center div vertically

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

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

1/* No Flexbox */
2.parent {
3  position: relative;
4}
5.child {
6  position: absolute;
7  top: 50%;
8  transform: translateY(-50%);
9}
10
11/* With Flexbox */
12
13.parent {
14  display: flex;
15  flex-direction: column;
16  justify-content: center;
17}
18
19
20

1/*Remove comment to become a better programmer. */
2/* No Flexbox */
3.parent {
4  position: relative;
5}
6.child {
7  position: absolute;
8  top: 50%;
9  transform: translateY(-50%);
10}
11
12/* With Flexbox */
13
14.parent {
15  display: flex;
16  flex-direction: column;
17  justify-content: center;
18}
19

1/* 100vh = 100% Viewport Height */
2body {
3	display: flex;
4	height: 100vh;
5	flex-direction: column;
6	justify-content: center;
7}
8/* add */ align-items: center; /*to also center horizontally.*/

1/* center vertically */
2/* No Flexbox */
3.parent {
4  position: relative;
5}
6.child {
7  position: absolute;
8  top: 50%;
9  transform: translateY(-50%);
10}
11
12
13
14/* With Flexbox */
15
16.parent {
17  display: flex;
18  flex-direction: column;
19  justify-content: center;
20}