Content character encoding in CSS3

The content has 5 properties

Content: ""; is empty

Content:attr (title); You can get a tag property value or you can get a custom property value such as

CSS is div:after{content:attr (Gaga)} then you can get to 123.

Content: "Who am I"; Fill in a string such as

CSS is div:after{content: "I Am" counter (title) ", I am afraid" counter (Gaga); The result is "I am GAGA2, I am afraid of gaga1";

Content: "\21e0"; Gets the character set icon of the figure below the slash is escaped but there are some icons in the browser directly there are some differences

Content:url (123.gif); Inserts an external resource (image, audio, video, or any other resource supported by the browser) using the specified absolute or relative address

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