css的选择器

id   方法精确

#div1 {
font-size:30px;
}

<!DOCTYPE html>
<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
    #div1 {
    font-size:30px;
    }
    </style>
  </head>
  <body>
    <p>段落</p>
    <p>段落</p>
    <p>段落</p>
    <p>段落</p>
    <div id="div1">diyihgsddg</div>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
  </body>
</html>

class  按类

.red {

        color:red;

     }

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
        .red {
        color:red;
        }
        .size40{
        font-size:40px;
        }
        
</style>
  </head>
  <body>
    <p>段落</p>
    <p>段落</p>
    <p>段落</p>
    <p class="red">段落</p>
    <div class="red">diyihgsddg</div>
    <div class="red size40">diyihgsddg</div>
    <!--class嵌套-->
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
  </body>
</html>

标签选择:div,p不精确,面广

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css</title>
    <style type="text/css">
div {
    color:red;
   }
   p {
   font-size:50px;}
</style>
  </head>
  <body>
    <p>111111111111</p>
    <p>222222222222</p>
    <p>333333333333</p>
    <p>555555555555</p>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
  </body>
</html>

交集选择

        div.red {
        color:red;
        }   
<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
        div.red {
        color:red;
        }   
</style>
  </head>
  <body>
    <p>段落</p>
    <p>段落</p>
    <p>段落</p>
    <p class="red">段落</p>
    <div class="red">diyihgsddg</div>
    <div class="red size40">diyihgsddg</div>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
  </body>
</html>

并集选择器

        div,p,li{
        color:green;
        font-size:30px;
        }
<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
        div,p,li{
        color:green;
        font-size:30px;
        }
</style>
  </head>
  <body>
    <p>段落</p>
    <p>段落</p>
    <p>段落</p>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
    <div>diyihgsddg</div>
    <ul><li>123</li><li>456</li></ul>    
  </body>
</html>

 子后代关系

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
div p{
color:green;}
</style>
  </head>
  <body>
    <div>
      <p>我是div里面的p</p>
      <p>我是div里面的p</p>
      <p>我是div里面的p</p>
    </div>
  </body>
</html>

后代的后代

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
div p{
color:green;}
div li{
color:yellow;}
</style>
  </head>
  <body>
    <div>
      <p>我是div里面的p</p>
      <p>我是div里面的p</p>
      <p>我是div里面的p</p>
    </div>
    <div>
      <ul>
        <li>123456</li>
        <li>123456</li>
      </ul>
    </div>
  </body>
</html>

伪类 a:hover鼠标放上去变色

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
a:hover{color:red;}/*hover鼠标放上去变色*/
</style>
  </head>
  <body>
    <a href="http://www.baidu.com">百度</a>
  </body>
</html>

*通配选择器 选中所有元素

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
*{
font-size:30px;}
</style>
  </head>
  <body>
    <p>aaaaaaaaaaaaaaaaaaa</p>
    <p>aaaaaaaaaaaaaaaaaaa</p>
    <a href="http://www.baidu.com">百度</a>
  </body>
</html>

body继承 类似于*

<html>
  <head>
    <meta name="generator"
    content="HTML Tidy for HTML5 (experimental) for Windows https://github.com/w3c/tidy-html5/tree/c63cc39" />
    <meta charset="utf-8" />
    <title>css给网页装潢</title>
    <style type="text/css">
body{
font-size:30px;}
</style>
  </head>
  <body>
    <p>aaaaaaaaaaaaaaaaaaa</p>
    <p>aaaaaaaaaaaaaaaaaaa</p>
    <a href="http://www.baidu.com">百度</a>
  </body>
</html>
原文地址:https://www.cnblogs.com/Yimi/p/5866225.html