Css hack + _*! Important

Common css hack:

CSS hack has different understandings of CSS parsing in different browsers, such as Internet Explorer 6, Internet Explorer 7, and Mozilla Firefox, which leads to different page effects, not what we need
Page effect.
At this time, we need to write different CSS for different browsers so that they can be compatible with different browsers at the same time, so that we can get the desired page effect in different browsers.

+ Background-color: red;/* ie10 ff not recognized */

* Background-color: red;/* ie10 ff not recognized */

_ Background-color: red;/* ie 5 6 recognition */

Background-color: red! Important;/* ie ff supports ie6 not */

The above code is tested in winnt, and xp is slightly different.