H5 ：
1. Semantic tags: header, footer, nav, section, article, aside
2. Form input type: email, tel, url, number
3. Form attributes: autocomplete, placeholder, form
4. Video and audio: audio, video
5. Drag and drop attribute: draggable
6. Class name operation: classlist
7. Web storage:
The size of the cookie does not exceed 4kb, and each request will be sent back to the server, and it will be valid before the set expiration time, even if the browser is closed
h5 provides:
localStorage: The data is always valid until it is manually deleted. Cross-browser invalid, the local database provided by the browser is at least 250kb, and there is even no upper limit
localStorage.setItem(key,value)
locatStorage.getItem(key)
localStorage.removeItem(key)
sessionStorage: Based on the session, the data disappears after closing the browser, 5M in size, invalid across browsers
C3 ：
1、选择器：nth-child（）、nth-of-type（）、：checked、：disabled
2. Box model:
3、背景：background-image、background-size、background-origin
4、渐变：linear-gradient、radial-gradient
5、边框：border-radius、border-image
6. Shadow: box-shadow, text-shadow
7、2D/3D转换：transform：translate rotate scale
8. Transition: transition
9. Animation: keyframes, animation
10: Flexible box: flex
11: Media inquiries: @media