1.bootstrap 预定义类clearfix和visible-xs-block
https://blog.youkuaiyun.com/u013182438/article/details/69942934
https://blog.youkuaiyun.com/FE_dev/article/details/68954481
2.float与高度塌陷
https://blog.youkuaiyun.com/chris_z_0622/article/details/65442975
3.Absolute
http://www.w3school.com.cn/css/css_positioning_absolute.asp
https://www.cnblogs.com/hjvsdr/p/7339638.html
4.css 组件的8种基本类型
5.巧妙使用负的外边距:
6.
8.ToDealWith:Bootstrap一个按钮与一个按钮之间的1象素细节引起的冲突:
.btn-group .btn +.btn{
margin-left:-1px
}
9.`css中“~”和“>”和“+”是什么意思:https://blog.youkuaiyun.com/XA5851477/article/details/65629214
10.