What is CSS? Are there any features and benefits?

CSS is a cascading style sheet that is mainly used to define fonts, borders, colors, etc. for web pages. There are many advantages, the main one is to facilitate the aesthetics of the web page. For example, if you know this page, you check IE's"View the source**"Thereinto.

It's just a call to a CSS file.

It should be a stylesheet for web text.

Answer]: Advantages: The great advantage is that it is concise, for a large website, it can save a lot of bandwidth, and as we all know, search engines like to clean (the real meaning is that it increases the proportion of effective keywords in the total number of web pages), so the use of CSS div's web standard to make ** has a certain advantage of search engine friendliness.

The high reliance on CSS makes web design more complex. Relative to the ** layout (table), although CSS+div is not unattainable, but at least it is much more complex than the ** fixed hunger position, even for the ** design master is easy to have problems, let alone beginners, which to a certain extent affects the popularization and application of the XHTML design language. File exceptions will affect the normal browsing of the entire **.

The design elements of CSS are usually placed in several external files, and this one or several files may be quite complex, or even relatively large, if the CSS file call is abnormal, then the whole ** will become miserable. 3。For CSS** design, the compatibility issue is more prominent.

The web design based on the web design has almost no browser compatibility issues in later versions, but the ** page collapse pants that are normally displayed in the Internet Explorer may be unrecognizable in Firefox (which is why it is recommended for online marketers to use Firefox). CSS+div needs to be further supported by various browser vendors. The decision on SEO is based on the professionalism of web design rather than CSS+div itself.

CSS+div web design does not guarantee the optimization of the web page to the search engine, and even does not guarantee that it must have a more concise design than HTML, not to mention that the search engine's inclusion and sorting of the web page is obviously not measured by whether it adopts ** and CSS positioning, which is why many traditional **layout production** are ranked high in the search results, and many web pages made using CSS and Web standards are still ranked low. Because for search engines, factors such as structure, content, and relevant links are always the most important indicators of optimization.

CSS is a cascading style sheet.

Cascading Style Sheets are a computer language used to express file styles such as HTML (an application of the Standard Markup Language) or XML (a subset of the Standard Markup Language). CSS can not only decorate web pages statically, but also dynamically format web page elements with various scripting languages.

CSS provides pixel-precise control over the placement of elements in web pages, supports almost all font size styles, and has the ability to style web page objects and models. CSS provides a style description for the HTML markup language that defines how elements are displayed in it. CSS is a breakthrough in the field of web design.

It can be used to modify a small style and update all the page elements associated with it.

How CSS works

CSS is a language that defines style structures such as fonts, colors, positions, etc., and is used to describe the way information is formatted and displayed on the Internet's remaining pages. CSS styles can be stored directly on an HTML web page or in a separate style sheet. Either way, a style sheet contains rules for applying a style to an element of a specified type.

When used externally, the style sheet rules are placed in an external style sheet document with a file extension css.

Style rules are formatting instructions that can be applied to elements in a web page, such as paragraphs of text or links. A style rule consists of one or more style attributes and their values. The internal style sheet is placed directly in the web page, the external style sheet is saved in a separate document, and the web page links to the external style sheet via a special tag.

The name "Cascading" in CSS indicates how the style list notice rule is applied to an HTML document element. Specifically, the styles in the CSS style sheet form a hierarchy, and more specific styles override the generic styles. The priority of style rules is determined by CSS according to this hierarchy, resulting in a cascading effect.

The above content refers to Bailiang Tanminco-css

The advantages of div+css are as follows:

1. It can make ** streamlined, use div + css layout to make ** very streamlined, and the css file can be called on any page of **, avoiding the use of table ** to modify part of the page with a circle.

2. The speed of web page access has been improved, and the DIV+CSS layout has been reduced a lot compared with the traditional table layout, and the browsing and access speed has been naturally improved, thereby improving the user experience.

3. It is conducive to optimization. The use of div-css layout is very friendly to search engines, concise and structured** is more conducive to highlighting the key points and suitable for search engine crawling.

4. Browser compatibility. div+css is more likely to have the problem of multiple browsers being incompatible with the previous grinding, mainly because different browsers have different defaults for web standards.

5. It should be noted that web pages don't like a page with too much CSS**, otherwise it will also affect the crawling of spiders and the inclusion of search engines, so it is a very good way to call CSS by external calls.

6. If you don't have to be too fancy, you can also achieve the desired effect by using CSS layout. Such as text color change in navigation, CSS drop-down menu, etc.

Pros of div+css:

1.Better control over web layout: div+css can better control web layout, making web page layout more flexible, easier to maintain, and easier to achieve complex layout effects.

3.Better maintainability: div+css can better realize the maintainability of web pages, making web pages easier to maintain, easier to achieve complex layout effects, and easier to achieve complex functions.

4.Better browser compatibility: DIV+CSS can better achieve browser compatibility of web pages, making it easier for web pages to display normally on multiple browsers and easier to achieve complex layout effects.

5.Better performance: DIV+CSS can better realize the performance of Lishen web pages, making web pages easier to crawl by search engines, easier to access, and easier to achieve complex layout effects.

Cascading, Inheritance, and Prioritization are the three features we must master to learn CSS.

1. CSS cascading.

Refers to the overlay of multiple CSS styles, which is an ability of the browser to deal with conflicts, if a property is set to the same element by two identical selectors, then one property will cascade the other.

For example, if you specify a label with red and then blue, and then specify a label with different values for the same style, this is a style conflict.

In general, if there is a style conflict, the CSS writing order will be followed, and the last style will prevail.

1.Styles conflict, follow the principle of proximity. That style is close to the structure, and that style is executed.

2.The styles do not clash and do not cascade.

The final mantra for execution: The back waves of the Yangtze River push the front waves, and the front waves die on the beach.

2. CSS inheritance.

Inheritance means that when writing a CSS stylesheet, child tags inherit certain styles of the parent tag, such as text color and font size. To set an inheritable property, simply apply it to the parent element.

The simple understanding is: the son inherits the father's business.

The final execution mantra of CSS: Dragons give birth to dragons, phoenixes give birth to phoenixes, and children born of mice will make holes.

Note: Proper use of inheritance can simplify and reduce the complexity of CSS styling. Child elements can inherit the style of the parent element (text-, font-, line - all of which start with these elements, as well as the color attribute).

3. CSS priority.

When defining CSS styles, it is common for two or more rules to be applied to the same element, and this is when the issue of precedence arises. When considering weights, beginners also need to pay attention to some special cases, which are as follows:

1.The weight of the inheritance style is 0. That is, in a nested structure, no matter how much weight the parent element's style is, when it is inherited by the child element, its weight is 0, which means that the style defined by the child element will override the inherited style.

2.Inline style takes precedence. The weight of the inline style is very high for elements that apply the style attribute, which can be understood to be much greater than 100. In short, he has a greater priority than any of the selectors raised above.

3.When the weight is the same, the CSS follows the principle of proximity. This means that styles that are close to the element have the highest priority, or the styles that are last in line have the highest priority.

Define one! important command, which is given the highest priority. That is, regardless of the weight and the distance of the style position, !important, all have the highest priority.

1.Greatly reduce pages**, improve page browsing speed, and reduce bandwidth costs;

3.Shorten the revision time. A site with hundreds or thousands of pages can be redesigned with just a few CSS modifications.

4.Powerful font control and typography capabilities. CSS is much better than bad font tags, and with CSS we no longer need to use font tags or transparent 1 px gifs to control titles, change font colors, font styles, etc.

Very easy to write. You can write CSS as easily as you can write HTML.

6.Improve ease of use. HTML can be structured using CSS.

7.Design once, publish anywhere.

8.Better control over page layouts.

CSS inheritance means that a child element inherits certain style attributes of the parent element, for example, if the parent element defines a font color (color attribute), the child element will inherit the font color of the parent element. However, we should note that not all elements are inherited, such as padding, margin, border, etc., are not inherited, and only those properties that can make it easy for us to write can be inherited.

1.Save space and bandwidth, for example, there are 10 places on a web page that have the same effect, with attributes such as length, width, color, font size, etc. If you don't use CSS, you might be setting the properties in those 10 places repeatedly, but with CSS, you only need to set it once in the style, and you can call the CSS in those 10 places, which greatly reduces bandwidth and space.

2.Porting and programming aspects. A div is like a box, and when you become proficient, you will find that using div+css to make web pages is as convenient as building blocks.

It's a house, CSS is decoration, put the decoration style together, it's much easier to modify, you don't need to change the html**; The biggest part is that you can have n decoration styles (CSS) that you can change as you like without destroying the house (HTML).

2.CSS can also do some things that HTML can't.

I'll just put it simply: CSS** is more optimized, eliminating bloat**, better web page layout, HTML is full of various attributes of tags to define the effect to be displayed, **will be a lot and later maintenance troublesome.