简体中文(ZH-CN) English(EN) 繁体中文(ZH-TW) 日本語(JA) 한국어(KO) Melayu(MS) Français(FR) Deutsch(DE)
Home > Web Front-end > HTML Tutorial > body text

The role of !important in CSS

WBOY
Release： 2016-12-05 13:26:28
Original
1968 people have browsed it

Increase the application priority of specified style rules.

  • There is a relatively explicit support problem in browsers IE6 and below. !important does not take effect in the same rule set. Please look at the following code:

    Sample code:

    div { color: #f00 !important; color: #000; }

    In the above code, the text color of the div in IE6 and below browsers is #000, !important does not override the following rules; the text color of the div in other browsers is #f00

  • To make !important take effect in IE6 and below browsers, you can use the following code:

    Sample code:

    div { color: #f00 !important; } div { color: #000; }

    In the above code, the text color of div in IE6 and below browsers is consistent with other browsers, both are #f00

　In IE6 and earlier browsers, !important does not take effect in the same rule set.

Example: 

<span style="color: #008080"> 1</span> <span style="color: #0000ff"><!</span><span style="color: #ff00ff">DOCTYPE html</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 2</span> <span style="color: #0000ff"><</span><span style="color: #800000">html</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 3</span>   <span style="color: #0000ff"><</span><span style="color: #800000">head</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 4</span>     <span style="color: #0000ff"><</span><span style="color: #800000">title</span><span style="color: #0000ff">></span>important的使用<span style="color: #0000ff"></</span><span style="color: #800000">title</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 5</span>     <span style="color: #0000ff"><</span><span style="color: #800000">meta </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="content-type"</span><span style="color: #ff0000"> content</span><span style="color: #0000ff">="text/html; charset=UTF-8"</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 6</span> <span style="color: #0000ff"><</span><span style="color: #800000">style</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 7</span> <span style="background-color: #f5f5f5; color: #800000">.button </span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080"> 8</span> <span style="background-color: #f5f5f5; color: #ff0000">    position</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> relative</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080"> 9</span> <span style="background-color: #f5f5f5; color: #ff0000">    background-color</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> #4CAF50</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">10</span> <span style="background-color: #f5f5f5; color: #ff0000">    border-radius</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">8px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">11</span> <span style="background-color: #f5f5f5; color: #ff0000">    font-size</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 28px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">12</span> <span style="background-color: #f5f5f5; color: #ff0000">    color</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> #FFFFFF</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">13</span> <span style="background-color: #f5f5f5; color: #ff0000">    padding</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 20px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">14</span> <span style="background-color: #f5f5f5; color: #ff0000">    width</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 200px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">15</span> <span style="background-color: #f5f5f5; color: #ff0000">    text-align</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> center</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">16</span> <span style="background-color: #f5f5f5; color: #ff0000">    transition-duration</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 1.5s</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">17</span> <span style="background-color: #f5f5f5; color: #ff0000">    overflow</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> hidden</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">18</span> <span style="background-color: #f5f5f5; color: #ff0000">    cursor</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> pointer</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">19</span>   <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">20</span> <span style="background-color: #f5f5f5; color: #800000">  .button:hover</span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080">21</span> <span style="background-color: #f5f5f5; color: #ff0000">    box-shadow</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">0 4px 8px 0 rgba(0,0,0,0.1),0 6px 20px 0 rgba(0,0,0,0.299)</span><span style="background-color: #f5f5f5; color: #000000">;</span>  
<span style="color: #008080">22</span>   <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">23</span> 
<span style="color: #008080">24</span> <span style="background-color: #f5f5f5; color: #800000">  .button:after </span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080">25</span> <span style="background-color: #f5f5f5; color: #ff0000">    content</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> ""</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">26</span> <span style="background-color: #f5f5f5; color: #ff0000">    background</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> #90EE90</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">27</span> <span style="background-color: #f5f5f5; color: #ff0000">    display</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> block</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">28</span> <span style="background-color: #f5f5f5; color: #ff0000">    position</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> absolute</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">29</span> <span style="background-color: #f5f5f5; color: #ff0000">    padding-top</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 300%</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">30</span> <span style="background-color: #f5f5f5; color: #ff0000">    padding-left</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 350%</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">31</span> <span style="background-color: #f5f5f5; color: #ff0000">    margin-left</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> -20px!important</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">32</span> <span style="background-color: #f5f5f5; color: #ff0000">    margin-top</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> -120%</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">33</span> <span style="background-color: #f5f5f5; color: #ff0000">    opacity</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 0</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">34</span> <span style="background-color: #f5f5f5; color: #ff0000">    transition</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">1s</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">35</span> <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">36</span> 
<span style="color: #008080">37</span> <span style="background-color: #f5f5f5; color: #800000">.button:active:after </span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080">38</span> <span style="background-color: #f5f5f5; color: #ff0000">    padding</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 0</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">39</span> <span style="background-color: #f5f5f5; color: #ff0000">    margin</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 0</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">40</span> <span style="background-color: #f5f5f5; color: #ff0000">    opacity</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 1</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">41</span> <span style="background-color: #f5f5f5; color: #ff0000">    transition</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">0s</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">42</span> <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">43</span> <span style="color: #0000ff"></</span><span style="color: #800000">style</span><span style="color: #0000ff">></span>
<span style="color: #008080">44</span> <span style="color: #0000ff"></</span><span style="color: #800000">head</span><span style="color: #0000ff">></span>
<span style="color: #008080">45</span> <span style="color: #0000ff"><</span><span style="color: #800000">body</span><span style="color: #0000ff">></span>
<span style="color: #008080">46</span> 
<span style="color: #008080">47</span> <span style="color: #0000ff"><</span><span style="color: #800000">button </span><span style="color: #ff0000">class</span><span style="color: #0000ff">="button"</span><span style="color: #0000ff">></span>Click Me<span style="color: #0000ff"></</span><span style="color: #800000">button</span><span style="color: #0000ff">></span>
<span style="color: #008080">48</span> <p>第31行的margin-left设置了!important，因此后面的第39行是不能更改margin-left的值。
<span style="color: #008080">50</span> <span style="color: #0000ff"></</span><span style="color: #800000">body</span><span style="color: #0000ff">></span>
<span style="color: #008080">51</span> <span style="color: #0000ff"></</span><span style="color: #800000">html</span><span style="color: #0000ff">></span>
Copy after login

Reference article:

http://www.runoob.com/css3/css3-buttons.html

http://www.css88.com/book/css/rules/!important.htm

This article is an original article by the blogger. If you need to reprint, please indicate the source.

Related labels：
CSS中!important的作用
source：php.cn
Previous article：HTML common tags Next article：Three ways to center an element vertically and horizontally
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Latest Issues
The page suddenly cannot pull css or bootstrap So I'm developing a page, I did part of it yesterday and it worked great, and today I cont...
From 2024-04-06 21:58:04
0
1
800
Is there a way to force the text in the flexbox to be vertically centered, no matter what other CSS code we have? I have the following CSS code that is part of a larger CSS code used in a website I'm deve...
From 2024-04-06 20:41:51
0
1
518
What are the best practices for displaying version information in web applications? I'm developing a web application. What are the best practices for displaying version infor...
From 2024-04-06 19:13:16
0
2
476
Scatterplot points do not maintain values ​​when zooming in d3.js This is my first time using d3.js, so please bear with me. I implemented it as pure JavaSc...
From 2024-04-06 18:16:26
0
1
403
Generate default values ​​and CSS variables using SCSS I'm implementing website styling. For legacy support reasons, I need to support IE11, at l...
From 2024-04-06 17:46:54
0
1
355
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn：Public welfare online PHP training，Help PHP learners grow quickly！