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What is CSS syntax? Detailed introduction to usage and rules

奋力向前Original: 2021-07-08 11:27:326836browse

In the previous article "What are HTML elements? A brief discussion on the grammatical rules of elements" takes everyone to understand HTML elements and grammatical rules. The following article will introduce you to CSS syntax and learn about the three ways to use CSS style sheets. Let’s take a look! !

1. CSS syntax

CSS rule set (rule-set) consists of selectors and declaration blocks

What is CSS syntax? Detailed introduction to usage and rules

Example explanation

p is the selector in CSS (it points to the HTML element to be styled ：<p></p>）

color is the attribute, red is the attribute value

text-align is the attribute, center is the attribute value

Code example:

<html>
<head>
<style>
p
{
	color:red;
	text-align:center;
} 
</style>
</head>
<body>
<p>php</p>
<p>php中文网</p>
</body>
</html>

Rendering:

What is CSS syntax? Detailed introduction to usage and rules

CSS Example:

CSS declarations always begin with a semicolon (;) ends, the statement is always enclosed in curly brackets ({}):

p 
{ 
color:red; 
text-align:center; 
}

Comments are used to explain your code, and you can edit it at will, the browser will ignore it.

CSS comments start with /* and end with */ . Examples are as follows:

/*这是个注释*/ 
p 
{ 
text-align:center; 
/*这是另一个注释*/ 
color:black; 
font-family:arial; 
}

2. How about CSS Instructions?

How to use CSS: Editing tools

There are generally three ways to use any text editing tool style sheet:

1) Document header Insert : Suitable for single web application

2) Insert in line: Suitable for CSS

3 in one or two places on the page )External link style file: Suitable for multiple web pages that use CSS

There are different ways to use css in HTML web pages and different ways to call css

1. Header Insert style internally

<style type="text/css">……</style>

Code example:

<html>
<head>
<title>中文网(php.com)</title>
<style type="text/css">
body {background-color:yellow;}
h1   {font-size:36pt;}
h2   {color:blue;}
p    {margin-left:50px;}
</style>
</head>
<body>

Note: Here the type attribute of the style object is set to”text/css ” is not supported by browsers that ignore stylesheets.

2. Inline insertion style

<p style=“font-size:16pt;color:blue”>蓝色16号文字</p>

adopts <style style="background-color: rgb(248, 248, 248);">font-size:16pt;color:blue"&gt The format of ;</style> writes the style in any line in HTML, which is more convenient and flexible.

3. External link style

First create an external style sheet file (.css), and then use the HTML link object

<head>
<title>中文网(php.com)</title>
<link rel=stylesheet
href="http://www.php.cn/php.cn"
type="text/css">
</head>

This method is very suitable for defining multiple documents at the same time. It enables multiple documents to use the same style at the same time, thereby reducing a lot of redundant code.

In XML, you should add it in the declaration area as shown in the following example:

<? xml-stylesheet type="text/css" href="http://www.php.cn/php.css" ?>

Define an internal style block object (Embedding a Style Block)

You can insert a <style>...</style># between the and

tags in your HTML document. ##Block object.

Notes

Be careful<p></p>

Recommended study:

CSS video tutorial

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