I want to buy a classic book, please recommend it_html/css_WEB-ITnose

I am a teacher in a county-level junior high school. Because I want to make something for the school, I finally applied to the leader to buy a professional book. I chose it online for a few days and couldn’t make up my mind, so I came here to ask everyone for advice.
1. Is div css or html5 css3 the mainstream now?
2. I want to buy a classic textbook that I can slowly learn or collect in the future. Please recommend it.

Reply to discussion (solution)

If you are interested in doing some web development on mobile devices, then HTML5 css3.
If it is still basic On PC, that's fine.
Recommend h5

If you are interested in doing some web development on mobile devices, then HTML5 css3.
If you are still basically on a PC, you can do it.
Recommend h5

Do you have any good books? Can you recommend one?

If you want to learn quickly, watch the video directly. HTML/CSS videos can be purchased for dozens of GB for 1 yuan on Taobao. ;
If you want to read a book, just search it on Baidu, then download the PDF version, read it at a computer store, and practice while reading;
Technology like the page is not purely theoretical, and the reading effect is slow.

If you want to buy a book, you can refer to "Crazy HTML5, CSS3 Lecture Notes", or

Authoritative Guide to HTML5 and CSS3 Try the authoritative guide~

It is recommended to use div css because You have to consider the compatibility of the browser. IE6 still has a high share in government departments and institutions

In fact, it is very fast to watch videos directly on MOOC.