1. Introduction to CSS
Cascading style sheet (Cascading style Sheet), referred to as CSS, is a computer language used to express file styles such as HTML or XML. It is also a style design language that can truly separate web page performance and content. It can control the position and layout of objects in web pages at the pixel level. It is currently the most widely used language for text-based display.
In the brisket publishing system, CSS is used to layout and control web pages. Next, let’s explain how CSS is introduced in HTML.
2. Introduction method
HTML and CSS are two languages with different functions. They affect a web page at the same time. Therefore, the two must be connected together to work properly. In HTML, there are four main ways to introduce CSS: inline, embedded, imported and link.
1) Inline
Inline is to set the CSS style in the style attribute of the tag. This method is only for A title produces an effect. This method essentially does not reflect the advantages of CSS, so it is rarely used in practice.
<head runat="server"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>HTML引入CSS</title></head><body> <h1 style ="color :cadetblue ;background-color : gray "> 行内式引入 </h1></body>
The above code is inline and only has an effect on this h1 title. It sets the text color to blue and the background color. is gray, the effect is as follows:
The setting of these elements is concentrated between
and , which is more suitable for a single web page. For multi-page websites, the introduction of inline will lose the advantages of CSS itself.In the above example, if you want all h1 tags in the page to use the same style, you can move the style to the head section and upgrade it to inline. The code is as follows:
The effect is as follows:
<head runat="server"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>HTML引入CSS</title> <style type="text/css" > h1 { color: cadetblue; background-color: gray; } </style></head><body> <h1>内嵌式引入CSS</h1> <h1>对整页h1标题产生效果</h1></body>3) Import formula
Introduce a separate CSS file into the HTML file. It is more widely used than the first two introduction methods. However, when using the imported style, the CSS file will not be loaded until the entire page is loaded. For some browsers with relatively large web page files, the unstyled page will be displayed first, and then the styled page will be displayed. The code is as follows:
h1 { /*mystyle.css*/ color :cadetblue;background-color: gray}/*HTML文档中style部分改为*/<style type ="text/css" > @import "mystyle.css"</style>
Link The same as the import method, it introduces an independent CSS file into the HTML file. But in terms of display effect, the CSS file will be loaded first and then the main part of the page, so the page will be displayed with style effects from the beginning, which is better than the imported style in terms of the viewer's experience. Introducing code directly deletes the imported style part, and adds the following statement in the head part (also the import method used in brisket):
There are two import methods: import and link. , all import independent CSS files. In addition to the above differences in display effects, there are also differences in ease of maintenance. When there are multiple CSS files, if you use link import, you need several statements to import the CSS files separately. If you want to adjust the classification of the entire CSS file, you need to adjust the HTML file, which is not conducive to maintenance. The import method can direct a general CSS file, and then import other independent CSS files in the file. Which introduction method is used depends on the specific situation.
<link href="mystyle.css" rel="stylesheet" type="text/css" />
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