level2

responsive design

rows:

columns: 

we can use multiple columns: 

we can use .col-md-*

we can do something like this

Adding row, make code easier to read

popular blogs with siding bar

leave one column as padding

Empty column 

much better way to leave padding 

实现不同size的设备上的不同显示：

遵循从小到大的继承

remain padding for book today!

 what if we only want the image to show on medium or large resolution?

we use .hidden-*

what is we want to show some image?

全栈老司机roadmap笔记--------Bootstrap (level 2)