Notation

Spacing utilities that apply to all breakpoints, from xs to xl, have no breakpoint abbreviation in them. This is because those classes are applied from min-width: 0 and up, and thus are not bound by a media query. The remaining breakpoints, however, do include a breakpoint abbreviation.

The classes are named using the format {property}{sides}-{size} for xs and {property}{sides}-{breakpoint}-{size} for sm, md, lg, and xl.

Where property is one of:

m - for classes that set margin  
p - for classes that set padding

Where sides is one of:

t - for classes that set margin-top or padding-top  
b - for classes that set margin-bottom or padding-bottom  
l - for classes that set margin-left or padding-left  
r - for classes that set margin-right or padding-right  
x - for classes that set both *-left and *-right  
y - for classes that set both *-top and *-bottom  
blank - for classes that set a margin or padding on all 4 sides of the element

Where size is one of:

0 - for classes that eliminate the margin or padding by setting it to 0  
1 - (by default) for classes that set the margin or padding to $spacer * .25  
2 - (by default) for classes that set the margin or padding to $spacer * .5  
3 - (by default) for classes that set the margin or padding to $spacer  
4 - (by default) for classes that set the margin or padding to $spacer * 1.5  
5 - (by default) for classes that set the margin or padding to $spacer * 3  
auto - for classes that set the margin to auto

(You can add more sizes by adding entries to the $spacers Sass map variable.)

ex: .col-md-6 : 970px, 分成12等分, md-6: 6/12 佔一半等分