What are the css selectors? Summary of css selector usage-CSS Tutorial-php.cn

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1. Selector (device) uses basic syntax
Selector { Attribute 1: Attribute value 1;
Attribute 2: Attribute value 2;
Attribute 3: Attribute value 3;
…..: …….;
}
2. Tag selector (directly use HTML tags as selectors)
second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>标记选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
</head>
<body>
    <p> 标记选择器(直接使用html标签做选择器)</p>
</body>
</html>

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second.css

p{
    font-size:34px;   
    text-align:left;    
    text-transform:uppercase;    
    font-family:黑体,宋体;    
    text-indent:3em;    
    text-decoration:line-through;    
    font-weight:bolder;    
    letter-spacing:0.5em;    
    line-height:3px;    
    margin:34px;    
    padding:23px;
    }

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3. Class selector (for each The label sets a class name. CSS can set the style of the label through the class name. Different labels can have the same class name, and they can share the same style.) - In CSS, label name.class name or .class name is used to express

second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>类选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
</head>
<body>
    <p  class="text"> 类选择器(为每一个标签设置一个类名，CSS可通过类名为标签设置样式，不同标签类名可以相同，
    相同可以共用同一个样式)---CSS中用标签名.类名或者.类名表示    </p>
</body>
</html>

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second.css

.text{
    font-variant:small-caps;/*小型大写字母*/
    font-family:宋体,黑体;    
    font-style:italic;    
    text-transform:lowercase;    
    font-size:35px;    
    text-indent:3em;    
    text-decoration:overline;    
    font-weight:bold;    
    letter-spacing: 1px;    
    line-height:3em;    
    font-variant:small-caps;    
    text-align:right;
    }

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4.ID selector (set a unique ID for each HTML tag, CSS can set the style for the tag through the id)
——#id value { } is used in CSS to represent

second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>ID选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <p  class="text" id="textp1"> ID选择器(为每一个HTML标签设置一个唯一的ID，CSS可以通过id来为标签设置样式)
    ----CSS中用#id值{ }来表示    </p>
    </body>
    </html>

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second.css

.text{
    font-variant:small-caps;/*小型大写字母*/
    font-family:宋体,黑体;    
    font-style:italic;    
    text-transform:lowercase;    
    font-size:35px;    
    text-indent:3em;    
    text-decoration:overline;
    }
#textp1{
    font-weight:bold;    
    letter-spacing: 1px;    
    line-height:3em;    
    font-variant:small-caps;    
    text-align:right;
    }

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5. Contains selectors (descendant selectors: can span generation, cross tags): Contain another tag in one tag
second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>包含选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <p  class="text" id="textp1">  <a href="#" class="link">ID选择器</a>
        (为每一个html标签设置一个唯一的ID，CSS可以通过id来为标签设置样式)
     ----CSS中用#id值{ }来表示    </p>
     </body>
     </html>

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second.css

p a{
    
    text-decoration:none;    
    font-size:25px;    
    background-color:pink;
    }
.text{
    font-size:21px;    
    font-style:normal;    
    text-transform:lowercase;    
    text-indent:3em;    
    font-weight:bold;    
    letter-spacing:0.7em;    
    line-height:27px;
    }

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6. Sub-selector (not supported by IE browser): No other tags can be included in the middle; in CSS, tag 1 > tag 2 (sub-tag) is used to represent

second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>子选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <p  class="text" id="textp1"> 
             <a href="#" class="link">子选择器</a>
            （IE浏览器不支持）：中间不能包含其他标签；CSS中 标签1 >标签2（子标签） 表示 
    </p>
    </body>
    </html>

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second.css

p>a{
    text-decoration:none;    
    font-family:黑体，宋体;
    }
p{    
font-size: 23px;
}

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7. Adjacent Selector: (CSS style is applied to the last tag) Commonly used to set column attributes of the table – CSS uses tag 1….Tag n represents

second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>相邻选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <p  class="text" > 
            子选择器:
            （IE浏览器不支持）：中间不能包含其他标签；CSS中 标签1 >标签2（子标签） 表示 
    </p>

    <p class="text1">
        相邻选择器(CSS样式作用在最后一个标签)常用设置表格的列属性--CSS用标签1+....标签n表示    </p>
        </body>
        </html>

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second.css

.text+.text1{
    color:pink;    
    background-color:gray;    
    font-size:34px;
    }

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8. Union selector: Set styles for multiple tags together, separated by commas

second.css

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>并集选择器</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <p  class="text" > 
            子选择器:
            （IE浏览器不支持）：中间不能包含其他标签；CSS中 标签1 >标签2（子标签） 表示 
    </p>

    <p class="text1">
        并集选择器:多个标签一起设置样式，用逗号隔开    </p>
        </body>
        </html>

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second.css

.text,.text1{
    color:pink;
    background-color:gray;    
    font-size:34px;}

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9. Pseudo class (a certain state of an element, often used to describe the state of a hyperlink: link (unvisited state); visited (visited state); hover (mouse passing state); active (clicking state) CSS tags Name: Status representation

second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>伪类</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <a href="" class="a1">伪类</a>
    </body>
    </html>

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second.css

a:link {
    color:blue;    
    font-size:53px;    
    text-decoration: none;
    }
a:visited {
    color:red;    
    font-size:193px;
    }
a:hover  {
    color:green;    
    font-size:73px;
    }
a:active  {
    color:gray;    
    font-size:183px;
    }

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10. Pseudo element (state of an element in an object) tag name in CSS : Pseudo-class representation
Commonly used ones are (first-letter [acts on the first letter of text], first-line [acts on the first line of text])
second.html

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>伪类</title>
    <link href="second.css" type="text/css"   rel="stylesheet">
    </head>
    <body>
    <p>伪元素(某个对象中某个元素的状态)CSS中用标签名：
 伪元素常用的有(first-letter[作用于文字首字]，first-line[作用于文字首行])  
 <br>伪元素(某个对象中某个元素的状态)CSS中用标签名：
 伪元素常用的有(first-letter[作用于文字首字]，first-line[作用于文字首行])    </p>
 </body>
 </html>

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second.css

p:first-letter{
    font-size:200%;
    }
p:first-line{
    color:red;
    }

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11 Style priority: Inline selector>ID selector>Class selector (pseudo-class, attribute)>Mark selector
You can use !important; to increase the priority
Related recommendations:

css class selector and id selector

##CSS descendant selector and multi-class selector

css tag selector, id selector, class selector instance

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