center a div in css

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

1.center {
2    position: fixed;
3    top: 50%;
4    left: 50%;
5    transform: translate(-50%, -50%);
6}

1.parent {
2  position: relative;
3}
4.child {
5    position: absolute;
6    left: 50%;
7    top: 50%;
8    transform: translate(-50%, -50%);
9}

1.parent {
2  position: relative;
3}
4.child {
5  position: absolute;
6  top: 50%;
7  left: 50%;
8  transform: translate(-50%, -50%);
9}

1/* Centering an element without flexbox */
2.parent-element {
3  position: relative;
4}
5
6.child-element {
7	position: absolute;
8  	left: 50%;
9  	top: 50%;
10  	transform: translate(-50%, -50%);
11}
12
13/* Centering an element using flexbox */
14.parent-element {
15	display: flex;
16  	align-items: center;
17  	justify-content: center;
18}

1.element {
2  position: absoloute;
3  margin: auto;
4  left: 0;
5  right: 0;
6  top: 0;
7  bottom: 0;
8}