Bootstarp Grid System

##### 1.3.2 Grid System

-a response-style grid system is defined in bootstrap
-The way to use it is to divide a container into 12 columns,
-then control the ratio of each column by the class name of the COL-XX-XX

##### 1.3.3.row Class

-Because each column defaults to a 15px left and right margin
-One function of the row class is to shield the margin from the left and right -15px

##### 1.3.4.col-*\*-\* Class

-col-xs-[number of columns]: show several in the ultra-small screen
-col-sm-[number of columns]: show several on the small screen
-col-md-[number of columns]: show several in the medium screen
-col-lg-[number of columns]: show several on the big screen
-__xs__: Ultra-small screen mobile phone (<768px)
-__sm__: Small screen tablet (≥768px)
-__md__: Medium-screen desktop display (≥992px)
-__lg__: Large screen large desktop display (≥1200px)

Responsive container container Grid layout 12 Parts A row of the number of parts mobile col-xs-4 a box accounted for 4 minutes small screen col-sm-4 in the screen col-md-4 large screen col-lg-4 do not meet the number of copies of a row will be left over the number of copies will fall away from the flow Container-fluid column offset: Col-xs-offset2 column sort backward: col-xs-push-9 sort forward Pull: col-xs-pull-3

Bootstarp Grid System