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This article is to share with you what are the knowledge points about CSS. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

1. Understanding and understanding of WEB standard and W3C

Tag closure, label lowercase, no random nesting, improve the search probability of the search robot

Using external chain css and js scripts, separation of structural behavior, faster file download and page speed

Content can be accessed by more users, content can be accessed by a wider range of devices, and less code and components

Easy to maintain, easy to modify, no need to change the content of the page

Provide a printed version without copying content and improve the ease of use of the website

2. What's the difference between xhtml and html

HTML is a basic WEB web design language, and XHTML is a markup language based on XML.

The main difference is:

XHTML elements must be nested correctly.

The XHTML element must be closed.

The XHTML signature must be in lowercase.

The XHTML document must have a root element.

3 、 Doctype? Strict mode and hybrid mode-how do you trigger these two modes and what's the point of distinguishing them?

Which specification (html/Xhtml) used to declare a document is generally a strict, excessive, framework-based html document

The declaration of joining XMl can be triggered, and the parsing method can be changed to IE5.5 's bug with IE5.5.

4. What are the elements in the line? What are the block-level elements? The box model of CSS?

Block-level elements: div p h 2 h 3 h 4 h 5 form ul

Inline element: a b br i span input select

Css box model: content, border,margin,padding

5. What are the ways of introducing CSS? What's the difference between link and @ import?

Introduction mode: inline, inline, outer chain, import

Difference between link and @ import:

Simultaneous loading

The former is not compatible, while the latter is not supported by browsers below CSS2.1

Link supports changing styles using javascript, which is not allowed

6. What are the CSS selectors? Which attributes can be inherited? How is the priority algorithm calculated? Which priority is higher, inline or important?

Selector: tag selector, class selector, id selector

Inheritance is not as good as specifying Id > class > tag selection.

Which is the higher priority of inline or important: the higher priority of important

7. What are the three layers of the front-end page and what are they? What is the function?

Structural layer: Html

Presentation layer: CSS

Behavior layer: js

8. What is the basic sentence composition of css?

Selector {attribute 1: value 1; attribute 2: value 2;. }

9. Which browsers have you tested the pages you made? What are the kernels of these browsers?

IE (IE kernel), Firefox (Gecko), webkit (Google), opear (Presto)

10. Write several solutions to IE6 BUG

Caused by two-sided BUG:float, using display

Pixel problem: caused by using float, using dislpay:inline-3px

The hyperlink hover fails when clicked: use the correct writing order linkvisited hover activen

IE z-index problem: adding position:relative to the parent

Png transparency: using js code to change

Minimum height of Min-height! Important solution'

Select masking under ie6: using iframe nesting

Why is there no way to define the width container around 1px (caused by the default row height of IE6, use over:hidden,zoom:0.08line-height:1px)

11 、

What is the difference between the title and alt attributes on the tag?

Alt: when the picture is not displayed, it is represented by words.

Title: provides information for this attribute

12. Describe the function and use of css reset.

The role of css reset: Reset resets the css default property of the browser

Use: different kinds of browsers, different styles, and then reset them to unify them.

13. Explain how to use css sprites.

Css sprites: integrate a bunch of small images into a large picture to reduce the number of requests for images from the server.

14. What is the difference between standard mode and weird mode of browsers?

Different rendering modes of box model

Use window.top.document.compatMode to show why the mode

15. How do you optimize the files and resources of the website? Expected solutions include:

File merging

File minimization / file compression

Using CDN hosting

Use of cach

16. What is semantic HTML?

Intuitive understanding of tags is good for the crawling of search engines.

17. Several ways to clear the float, their respective advantages and disadvantages

Clear the floating clear:both with an empty tag (in theory, it can be clear of any tag, add meaningless tags)

Use overflow:auto (empty tag elements clear floats and have to add unintentional code, use zoom:1 for compatibility with IE)

Thank you for reading! This is the end of this article on "what are the knowledge points of CSS?". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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