How does css align div horizontally and vertically in full screen mode?

How does css align div horizontally and vertically in full screen mode?

How does css align div horizontally and vertically in full screen mode:
This topic describes how to align a div element horizontally and vertically throughout the web page. The Code is the most convincing and you can directly look at the code.
The Code is as follows:

<! DOCTYPE html> 
The above code centers the div in full screen on the webpage. The following describes how to implement it.
I. Implementation principle:
Set the div element to absolute positioning, and set its left and right attribute values to 50% respectively. At this time, the div is not centered, and the center is the upper left corner of the div, therefore, we need to pull a certain distance from the top to the left, which is half of the height and width respectively.
Ii. Related reading:
1. Absolute positioning of CSS.
2. For details about negative margin values, refer to the margin-right attribute section of CSS.
The original address is: http://www.softwhy.com/forum.php? Mod = viewthread & tid = 14084.
For more information, see: http://www.softwhy.com/divcss/