Detailed explanation of implementation examples of CSS translucent borders (picture)

Detailed implementation example of CSS translucent border (picture)

1. Translucent border

Question:

If we want to set a red background and a black translucent border for a container, we might write like this:

border: 20px solid rgba(0,0,0,0.5);
background: red;

But the effect is like this (picture 1-1.png); Why does our translucent color not implement a translucent border?

Figure 1-1.png

Solution:

We can pass background-clipAttribute To adjust the default behavior above, set its value to padding-box, and then the effect we want will appear (Figure 1-2.png);

border: 20px solid rgba(0,0,0,0.5);
background: red;
background-clip: padding-box;

Figure 1-2.png

2.background-clip

Since the background-clip attribute is used, let's take a look at this attribute;

background-clip:

Set the background of the element (backgroundPicture or color) extends below the border.

Values ​​(values)	Description
border-box	Default initial value, the background extends to the outer edge of the border (but under the border)
padding-box	Nothing under the border Background, that is, the background extends to the inner margin outer edge
content-box	The background is cropped to the outer edge of the content area (content-box)
text	ExperimentAPI, the background is cropped into the foreground text.

示例

CSS content

span {
   border: 10px blue;
   border-style: dotted double;
   margin: 1em;
   padding: 2em;
   background: #F8D575;
}
.border-box { background-clip: border-box; }
.padding-box { background-clip: padding-box; }
.content-box { background-clip: content-box; }
.text { background-clip: text; }

 

HTML content

<span>border-box</span>
<span>padding-box</span>
<span>content-box</span>
<span>text</span>

 

效果：（图2-1.png）

图2-1.png

3.border-style

4.border-image

初始值：

• border-image-source: none

• border-image-slice: 100%

• border-image-width: 1

• border-image-outset: 0s

• border-image-repeat: stretch

4.1 border-image-source: none |

where

= | | | | |

where

= image([ [ | ]? , ? ]!)
= image-set(#)
= element( )
= cross-fade(,?)
= | | |

Gradient示例：

= linear-gradient( [ | to ]?, )

CSS content

.gradient { 
    border: 30px solid;
    border-image-source: linear-gradient(to right, red, green, blue);
    /*border-image-source: linear-gradient(90deg, red, green, blue);*/
    border-image-slice: 10;
    padding: 20px;
}

 

HTML content

<p>The image is stretched to fill the area.</p>

 

效果：（图4-1.png）

图4-1.png

4.2 border-image-slice: [ | ]{1,4}&& fill?

这个 border-imge-slice 属性传入1~4个参数（number没有单位专指像素或百分比值）将图片分割成9个部分,1,2,3,4四个区块是不会拉伸,不会平铺，称之为盲区，5,6,7,8四个区块可以通过 border-image-repeat 来控制拉伸平铺和重复（ stretch:默认值,拉伸; repeat:平铺; round:整数次平铺; ），第9区块不显示，传入参数 fill 则显示第9区块，分割情况如下图（图4-2.png && 图2-3.png）:

图4-2.png

图4-3.png

我们通过上面这张图片（81px^81px）来看传入不同个数的参数是如何分割这张图片的；

1个参数

/* border-image-slice: slice */
border-image-slice: 27; 
border: 30px solid transparent;
padding: 20px;
border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));

 

图4-4.png

图4-5.png(效果图)

2个参数（参考图4-3.png）

/* border-image-slice: vertical horizontal */
border-image-slice: 40 40.5; 
border: 30px solid transparent;
padding: 20px;
border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));

 

图4-6.png

图4-7.png(效果图)

3个参数

/* border-image-slice: top horizontal bottom */
border-image-slice: 27 40 27; 
border: 30px solid transparent;
padding: 20px;
border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));

 

图4-8.png（效果图）

4个参数(参考图4-2.png)

/* border-image-slice: top right bottom left */
border-image-slice: 27 40 27 27;
border: 30px solid transparent;
padding: 20px;
border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));

 

图4-9.png（效果图）

4.3 border-image-width: [ | | | auto ]{1,4}

语法：

border-image-width: all                        /* One-value syntax */       
E.g. border-image-width: 3;
border-image-width: vertical horizontal        /* Two-value syntax */  
E.g. border-image-width: 2em 3em;
border-image-width: top horizontal bottom      /* Three-value syntax */    
E.g. border-image-width: 5% 15% 10%;
border-image-width: top right bottom left      /* Four-value syntax */  
E.g. border-image-width: 5% 2em 10% auto;

 

设置边框图片的width，如果超出了设置的border-width,会向内扩展；查看下方示例，比较（图4-10.png && 图4-11.png）；

示例：

border: 30px solid transparent;
padding: 20px;
border-image-source: url("https://mdn.mozillademos.org/files/4127/border.png");
border-image-slice: 27;

 

图4-10.png

border: 30px solid transparent;
padding: 20px;
border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));
border-image-slice: 27;
border-image-width: 1 2 1 1;

 

图4-11.png

4.4 border-image-outset: [ | ]{1,4}

语法：

/* border-image-outset: sides */
border-image-outset: 30%;
/* border-image-outset:vertical horizontal */
border-image-outset: 10% 30%;
/* border-image-outset: top horizontal bottom */
border-image-outset: 30px 30% 45px;
/* border-image-outset:top right bottom left  */
border-image-outset: 7px 12px 14px 5px;

 

效果是将边框图片延伸到盒子外面，查看下放示例，比较（图4-12.png && 图4-13.png）；

示例:

border: 30px solid transparent;
 padding: 20px;
 border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));
 border-image-slice: 27;
 margin: 60px;

 

图4-12.png

border: 30px solid transparent;
padding: 20px;
border-image-source:url([https://mdn.mozillademos.org/files/4127/border.png](https://mdn.mozillademos.org/files/4127/border.png));
border-image-slice: 27;
margin: 60px;
border-image-outset: 2 1 1 1;

 

图4-13.png

4.4 border-image-repeat: [ stretch | repeat | round ]{1,2}

值（value）	说明
stretch	默认初始值 ，；拉伸
repeat	平铺
round	整数次平铺

语法：

border-image-repeat: type                      /* One-value syntax */       
E.g. border-image-value: stretch;
border-image-repeat: horizontal vertical       /* Two-value syntax */       
E.g. border-image-width: round space;

 

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