Source

Spacing

Bootstrap includes a wide range of shorthand responsive margin and padding utility classes to modify an element's appearance.

How it works

Assign responsive-friendly marginor paddingvalues ​​to an element or a subset of its sides with shorthand classes. Includes support for individual properties, all properties, and vertical and horizontal properties. Classes are built from a default Sass map ranging from .25remto 3rem.

notation

Spacing utilities that apply to all breakpoints, from xsto xl, have no breakpoint abbreviation in them. This is because those classes are applied from min-width: 0and 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 xsand {property}{sides}-{breakpoint}-{size}for sm, md, lg, and xl.

Where property is one of:

  • m- for classes that setmargin
  • p- for classes that setpadding

Where sides is one of:

  • t- for classes that set margin-toporpadding-top
  • b- for classes that set margin-bottomorpadding-bottom
  • l- for classes that set margin-leftorpadding-left
  • r- for classes that set margin-rightorpadding-right
  • x- for classes that set both *-leftand*-right
  • y- for classes that set both *-topand*-bottom
  • blank - for classes that set a marginor paddingon all 4 sides of the element

Where size is one of:

  • 0- for classes that eliminate the marginor paddingby setting it to0
  • 1- (by default) for classes that set the marginor paddingto$spacer * .25
  • 2- (by default) for classes that set the marginor paddingto$spacer * .5
  • 3- (by default) for classes that set the marginor paddingto$spacer
  • 4- (by default) for classes that set the marginor paddingto$spacer * 1.5
  • 5- (by default) for classes that set the marginor paddingto$spacer * 3
  • auto- for classes that set the marginto auto

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

Examples

Here are some representative examples of these classes:

.mt-0 {
  margin-top: 0 !important;
}

.ml-1 {
  margin-left: ($spacer * .25) !important;
}

.px-2 {
  padding-left: ($spacer * .5) !important;
  padding-right: ($spacer * .5) !important;
}

.p-3 {
  padding: $spacer !important;
}

horizontal centering

Additionally, Bootstrap also includes an .mx-autoclass for horizontally centering fixed-width block level content—that is, content that has display: blockand a widthset—by setting the horizontal margins to auto.

centered element 
<div class="mx-auto" style="width: 200px;">
  Centered element
</div>