We all should have browsed Tmall, Taobao, JD.com and other malls. When entering these malls, the navigation bar of the mall is usually on the left side of the page, as shown below

In order to facilitate users to quickly find the information category they want, when we click on the product in the picture above, another category will appear on the right, as shown below

These effects mainly use the hover effect of CSS, which is taught in this course How do you use our css to achieve these effects

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