Several CSS black technologies_html/css_WEB-ITnose

Original source: JellyBool (@JellyBool) Welcome to share the original to Bole Toutiao

Due to some reasons, I didn’t write a blog yesterday. I promised to post one post every day. This is To make up for what I did yesterday. Then I will become a clickbait. The black technology here is actually some properties in CSS that are not well known but are very useful in solving certain problems.

border-radius

Many developers probably do not understand this border-radius correctly, because basically many people use it this way:

CSS

1 2 3 .box {   border-radius: 4px; } 1 2 3

.box { border-radius: 4px; }

The slightly higher-end version is Like this:

1 2 3

.box {   border-radius: 4px 6px 6px 4px; }

CSS

However, the ultimate black technology is used like this:

CSS

1 2 3

1 2 3 .box {   border-radius: 5px 5px 3px 2px / 5px 5px 1px 3px; } .box { border-radius: 4px 6px 6px 4px; }

1	斜线前面的影响的是水平方向，斜线后面影响的是垂直方向，各个数字就分别代表四个不一样的方向。

1 2 3

.box { border-radius: 5px 5px 3px 2px / 5px 5px 1px 3px; }

Yes, it can be assigned 8 values, never seen it? Don’t worry, the specific explanation is as follows: CSS

1	The one before the slash affects the horizontal direction, and the one after the slash affects the vertical direction. Each number represents four different directions.

outline-offset

I believe many developers will be familiar with the following statement when writing CSS:

CSS

1 2 3 4 5 6 7

input {     outline : none; }   input:focus {     outline : none; }

1

2

3

4

5

6

7

input { outline : none;

}

1 2 3

input {     outline-offset: 4px ; }

input:focus {

outline : none;

}

This is how to remove the default blue line frame from the input box. In fact, another thing to mention here is that there is an outline-offset attribute in CSS. In this attribute, you can set the distance of the default wireframe; like this

CSS

1 2 3

.col-8 {   }

1 2 3

input { outline-offset: 4px; }

Adjust the size of this attribute value and you can see The distance to the outline changes. Class declaration Everyone may be familiar with the following class declaration: CSS

1 2 3

.col-8 { }

Of course it’s okay, but what if you write it like this:

CSS

1 2 3 4 5 6 7 .? {   color: hotpink; }   .★ {   color: yellow; } 1 2 3 4 5 6 7

.? { color: hotpink; } 1 .★ { color: yellow; }

Well, how does it look, you can use it like this:

1 2 3 4 5 6 7

ol li:nth-child(n 7):nth-child(-n 14) {   background: lightpink; } /** Or Safari Way **/ ol li:nth-child(-n 14):nth-child(n 7) {   background: lightpink; }

CSS

1

As long as it is Unicode, you can declare your class like this. Select several consecutive elements CSS

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ol li: nth-child(n 7):nth-child(-n 14) { background: lightpink; } /**Or Safari Way **/ ol li:nth-child(-n 14):nth-child(n 7) { background: lightpink; }

The above writing method can actually select the seventh to fourteenth li elements below ol.

Pseudo class setting single tag

There are several common single tags in HTML:
,

---

etc. Details can be found here:

http://www.w3.org/TR/html5/syntax.html#void-elements

The following example is to modify

---

.

CSS

1 2 3 4 5 6 7 hr:before {     content: "??"; }   hr:after {     content: " This is an element"; } 1 2 3 4 5 6 7

hr:before { content: "?? "; } 1 display: block hr:after { content: " This is an element"; }

Yes, the key is to use the :before and :after pseudo-classes. Here, by the way, you can actually use these two pseudo-classes to modify and , but the premise is that you set the display attributes of these two to:

CSS

1 2

1	display: block td>

Attributes are case sensitive Suppose we have code similar to the following when writing html: XHTML

1 2	< div class="box">

Then we use attribute selectors for CSS modification:

3

4

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div [class="box"] {   color: blue; }   input [type="email"] {   border: solid 1px red; }

5 6

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div [class="box"] {

color: blue;

}

input [type="email"] {

border: solid 1px red;

}

1 2 3 4 5 6 7

div [class="BOX"] {   color: blue; }   input [type="EMAIL"] {   border: solid 1px red; }

Such a statement The method will undoubtedly work. However, if we declare it like this, what will the result be like: 🎜> 3 4 5 6 7 div [class="BOX"] { color: blue; } input [type="EMAIL"] { border: solid 1px red; }

After this becomes uppercase, the first class="BOX" will not affect

, and the second type ="EMAIL" will still be modified normally . So when using attribute selectors, pay attention to capitalization issues.

Currently, I just feel like I need to remind myself of these CSS black technologies, and I can add some.

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