CSS Introduction

CSS stands for Cascading Style Sheets (Cascading Style Sheets). CSS is a standard stylesheet language used to describe the presentation of web pages (i.e., layout and formatting).

Before CSS, almost all the presentation form attributes of HTML documents were included in the HTML markup (especially within HTML tags). All font colors, background styles, element alignment, borders, and sizes must be explicitly described in HTML.

The consequence of doing so is that since the style information is repeatedly added to each page of the website, the development of large websites becomes a long and expensive process, and also increases the cost of maintenance.

To address this issue, the World Wide Web Consortium (W3C)1996In the year CSS was introduced, the W3C also maintained its standards. CSS aims to separate presentation and content. Now, web designers can move the formatting information of web pages to separate style sheets, thus greatly simplifying HTML markup and improving maintainability.

CSS3The latest version of the CSS specification. CSS3New style features and improvements have been added to enhance the Web demonstration function.

What can CSS do

CSS can do more.

• You can easily apply the same style rules to multiple elements.

• You can use a stylesheet to control the display of multiple pages on a website.

• You can display the same page in different ways on different devices.

• You can set the style of the dynamic state (such as hover, focus, etc.) of the element, which is otherwise not possible.

• You can change the position of an element on the web page without changing the markup.

• You can change the display of existing HTML elements.

• You can use2Or D3Transform, scale, rotate, skew, and other elements in D space.

• You can create animations and transition effects without using any JavaScript.

• You can create a print-friendly version of a web page.

There are many other interesting operations that can be performed with CSS. In the following chapters, you will learn in detail about all these contents.

The advantages of using CSS

The biggest advantage of CSS is that it can separate the styles and layouts from the content of the document. There are more advantages, why choose to use CSS?

• CSS saves a lot of time -CSS offers a lot of flexibility for setting the style properties of elements. You can write CSS once. Then the same code can be applied to groups of HTML elements, or reused across multiple HTML pages.

• Easy to Maintain — CSS provides a simple method to update the format of documents and maintain consistency between multiple documents. Because one or more style sheets can easily control the content of the entire web page.

• Faster Page Loading Speed -CSS allows multiple pages to share formatting information, thus reducing the complexity and redundancy of document structure content. It significantly reduces file transfer size, thereby speeding up page loading speed.

• Advanced Styles in HTML -CSS has a broader range of representation functions than HTML and can better control the layout of web pages. Therefore, compared with HTML representation elements and attributes, you can make your web pages look better.

• Multiple Device Compatibility -CSS also allows for optimizing web pages for various types of devices or media. With CSS, you can present the same HTML document in different viewing styles for different presentation devices (such as desktops, mobile phones, etc.).

Content covered in this tutorial

This CSS tutorial series covers all the basic knowledge of CSS, including the concept of selectors, methods for setting colors and backgrounds, ways to set the format of fonts and text, styling UI elements such as hyperlinks, lists, tables, and so on, as well as CSS box model, etc.

After familiarizing yourself with the basics, you will move on to the next level, which introduces setting the size and alignment of elements, methods for placing elements on the web page using image sprites, and concepts of relative and associated. Absolute units, visual formatting model, display and visibility, layers, pseudo-classes and elements, media-related style sheets, and more.

Finally, you will explore CSS3some advanced features introduced, such as gradient colors, shadow effects,2D and3D transformations, alpha transparency, methods for creating transitions and animation effects, flexible layout, filter effects, media concept queries, and more.