Detailed code explanation of how to implement various centered filling methods using css attributes

First ishorizontal centering. The simplest way is of course

margin:0 auto;

that is, to set the margin-left and margin-right attributes Set to auto to achieve a horizontally centered effect.

What about other ways?

line-height

First introduce the horizontal centering method of text:

刘放

Use line-height to be the same as height:

.wrap{ line-height: 200px;/*垂直居中关键*/ text-align:center; height: 200px; font-size: 36px; background-color: #ccc; }

The effect As follows:

padding filling

Use padding and background-clip to achieve the horizontal and vertical centering of p:

Set the backgroun-clip to content-box, crop the background to the outer edge of the content area, and then use padding to set it to half of the difference between the outer p minus the inner p:

.parent{ margin:0 auto; width:200px; height:200px; background-color:red; } .children { width: 100px; height: 100px; padding: 50px; background-color: black; background-clip:content-box;/*居中的关键*/

The effect is as follows:

margin filling

Next, we will introduce the method of margin filling to achieve horizontal and vertical centering.
First we define the parent and child p:

Here we set the margin-top of the child p to the height of the parent p minus half the height of the child p, and then set the overflow to hidden to trigger the parent The BFC and LESS code of p is as follows:

@parentWidth:200px; @childrenWidth:50px; .parent { margin:0 auto; height:@parentWidth; width:@parentWidth; background: red; overflow:hidden;/*触发BFC*/ } .children { height:@childrenWidth; width:@childrenWidth; margin-left:auto; margin-right:auto; margin-top: (@parentWidth - @childrenWidth) / 2; background:black; }

The final centering effect is as follows:

absolute positioning

Use position:absolute with top, left 50%, and then set margin to a negative value to center p horizontally and vertically. First, you still need to define the parent and child p:

and then set the corresponding css:

.parent { position:relative; margin:0 auto; width:200px; height:200px; background-color:red; } .children { position:absolute; left:50%; top:50%; margin:-25px 0 0 -25px ; height:50px; width:50px; background-color: black; }

The value in margin is half of the width of p. The final rendering is:

text-align is centered

As we all know, text-align can center the content in a p horizontally. But what if you want to center the sub-p in this p? You can set the display of sub-p to inline-block.

.parent { text-align:center; margin:0 auto; width:200px; height:200px; background:red; } .children { positiona;absolute; margin-top:75px; width:50px; height:50px; background: black; display:inline-block;/*使其父元素text-align生效*/ }

flex centering

Finally, let’s introduce the horizontal and vertical centering method implemented by display:flex in CSS3.

 
我是通过flex的水平垂直居中噢！
 

rrree

The effect is as follows:

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