[CSS] Positioning elements are displayed in the center

1. Use margin

p {
    width: 100px;
    height: 100px;
    background-color: skyblue;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-top: -50px;
    margin-left: -50px;}

## Analysis:

• top: 50%; left: 50%; Let the top left of the element be vertically and horizontally centered in the parent element

• margin-top: -50px; margin-left: -50px; Let The element is offset half its distance upward and to the right

p {
    width: 100px;
    height: 100px;
    background-color: skyblue;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);}

Analysis:

• top: 50%; left: 50%; Let the top left of the element be vertically and horizontally centered in the parent element

• transform: translate(-50%, -50%); Move the element up and to the right by half its distance

p {
    width: 100px;
    height: 100px;
    background-color: skyblue;
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right : 0;
    margin: auto;}

Analysis:

• All four directions When it is 0, they cancel each other out, and the box will be displayed at the initial position

• margin: auto; center the box vertically and horizontally