css style sheet refers to Cascading Style Sheets (CSS), a computer language used to express file styles such as HTML or XML, and a programming language used to express HTML styles. Language is a style language that can separate web pages and content.
The operating environment of this tutorial: Windows 7 system, CSS3 version, Dell G3 computer.
css style sheet generally refers to CSS (cascading style sheet).
Cascading Style Sheets (English full name: Cascading Style Sheets) are files used to express HTML (an application of Standard Generalized Markup Language) or XML (a subset of Standard Generalized Markup Language). The computer language of styles is a programming language used to express HTML styles. It is a style language that can separate web pages and content.
CSS is mainly used to design the style of web pages and beautify web pages; it can not only statically modify web pages, but also dynamically format various elements of web pages in conjunction with various scripting languages.
CSS can perform pixel-level precise control over the layout of element positions in web pages, supports almost all font size styles, and has the ability to edit web page objects and model styles.
Composition of css
css definition consists of three parts: selector, attribute, attribute value
选择符{属性:属性值;}
1. Selector: also known as Selectors, all tags in HTML language are controlled through different css selectors.
2. Attributes: mainly include font attributes, text attributes, background attributes, layout attributes, border attributes, list item attributes, table attributes, etc. Some of these attributes are only supported by some browsers, which makes the use of CSS attributes more complicated
3. Attribute value: is the valid value of a certain attribute. Attributes and attribute values are separated by ":" semicolons. When there are multiple attributes, use ";" to separate them.
Example:
(Learning video sharing:css video tutorial)
Note:h2is the selector;font-familyis the attribute; "宋体" is the attribute value
css selector
Commonly used ones include tag selector, category selector, id selector, etc.
1) Tag selector (also called element selector, type selector)
what: HTML page is composed of many tags, such as image tag, hyperlink tag, table tag
Example: