html5 / css3 base face questions

A, html5 What are the new features, to remove those elements, how to deal with browser compatibility issues new HTML tags? How to distinguish between HTML and HTML5?

New features:

1. Drag release (Drag and drop) API
2. Better semantic content tag (header, footer, section, nav, aside, article)
3. Audio, video API (audio, video)
4. Canvas API (Canvas)
5. Geographic API (Geolocation)
6. After long-term storage of data stored locally localStorage, browser closes data is not lost
7. sessionStorage data is automatically deleted when the browser is closed
8. Form controls, calendar, date, time, email , url, search
   the removal of elements:
9. Pure performance elements: font, basefont, big, center, s, strike;
10. Element can have a negative impact on the use of: frame, frameset, noframes;
    compatibility:
    IE8 / IE7 / IE6 support label produced by document.createElement method, you can use this feature to make these new browsers support HTML5 tags.
    How to distinguish:
    DOCTYPE declaration, the new structural elements, functional elements

Two, CSS3 What's new there?

1. Fillet (border-radius), the shadow (box-shadow)
2. Text effects (text-shadow), linear gradient (gradient), rotation (Transform)
3. More and more CSS selectors background rgba
4. Media queries, multi-column layout
5. border-image
6. The only pseudo-element is :: selection

Third, the description of the distinction cookies, sessionStorage and localStorage of:

Similarities: the client are stored in
different points:
1. Storage Size:
* cookies can not exceed the data size of 4K
* Although sessionStorage localStorage and store size is also limited, but larger than the plurality of cookies, can reach more than 5M
2. valid time :
* cookies will remain valid until the expiration time set cookies, even if the browser is closed
* localStorage to store persistent data, after the browser is closed automatically deleted unless the data is not lost
* sessionStorage current data is automatically deleted when the browser window is closed
3. data server interactive way:
* cookies data automatically to the server, the server can also write cookies are clients
* localStorage and sessionStorage not automatically transfer the data to the server, save only in the local

Four, CSS has a content property? what's the effect?

css 的 content 应用在 before/after 伪元素上，用来插入生成的内容。最常见是利用伪元素清除浮动

1. Why remove floating? How to remove floating?
   To prevent the collapse of the height of the problem. Parent elements provided overflow: hidden / auto;
   .clearfix::after{ content:" ", display:block; clear:both }