CSS common styles-HTML Tutorial-php.cn

CSS common styles

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Release： 2018-03-08 15:40:53

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This time I will bring you common CSS styles. What are the precautions for using common CSS styles? Here are practical cases, let’s take a look.

What does CSS Sprite (Sprite) refer to? What is its function

CSS Sprite is CSS Sprite, some people also call it CSS Sprite. It is a CSS image merging technology. The method is Merge the small icon and background image into one image, and then use CSS background positioning to display the part of the image that needs to be displayed.

What are the differences in usage scenarios between img tags and CSS background images?

img is used as an html tag, and the images used by img are generally used as content.
The CSS background image is generally used for decoration.
In a more detailed direction, during the loading process of the web page, the images that exist as css background images will not start loading until the structure is loaded (after all the content of the web page is displayed), and the img tag in html is the web page structure. Part of (the content) is loaded during the loading of the structure. The image is used as the background. When the image is not loaded or fails to load, there will be no placeholder mark for the image and no red cross will appear.

What are the functions of title and alt attributes?

The title attribute specifies additional information about the element. This information usually displays a ToolTip text when the mouse is moved over the element. The alt attribute specifies alternative text when the image cannot be displayed.

background:url(abc.png) 0 0 no-repeat;What does this sentence mean?

This sentence is the abbreviation of background, and url represents background- imageInsert the address of the background image. 0 0 represents the value of background-position, which indicates the positioning of the background image. The two before and after are horizontal positioning and vertical positioning respectively. The upper left corner is 0 0, and no-repeat represents the value of background-repeat. Available values are repeat, no-repeat, repeat-x, repeat-y, and inherit. Indicates respectively horizontal and vertical repetition, no repetition, only horizontal repetition, only vertical repetition, and inheritance from parent elements.

background-sizeWhat is the function? How is the compatibility? Commonly used values are?

background-size compatibility

How to center a div horizontally? How to center the picture horizontally

Center the div horizontally:
1. Margin method: by setting the margin on the div, margin: 0 auto;
2. display: inline-block method: parent element Set text-align:center. You need to set display:inline-block on the div in the play.
3. Floating method: For div and its parent element, float:left, relative positioning, parent element left50%, div right 50%.
Horizontally center the image: Put the image into a block-level element, using the above method.

How to set an element to be transparent? Compatibility?

You can set the speech rate transparency through rgba and opcity. For browsers of ie8 and worse versions, you need to add filter:alpha(opacity=x).

opacity and rgba can be set to be transparent, what is the difference?

opacity will inherit the opacity attribute of the parent element, while the descendant elements of the element set by RGBA will not inherit the opacity attribute.

<html> <head> <meta charset="UTF-8"> <title>Document</title> <style type="text/css">
           .rgba,.opacity{                 margin:0 auto;                 width:200px;                 height: 200px;                 text-align: center;                 line-height: 200px;                 font-size: 20px;                 border:1px solid black;             }             .rgba{                 background: rgba(255,0,0,0.5);             }             .opacity{                 background: red;                 opacity: 0.5;             }         </style>     </head>     <body>         <div class="rgba">             这是RGBA不透明度         </div>         <div class="opacity">             这是opacity不透明度         </div>     </body>     </html>

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, it can be proved that opacity can inherit the attributes of the parent element. In addition, opacity can also set the transparency of the image.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!