Spacing

Spacing utility is used to assign the responsive-friendly margin or padding values to an element or a subset of its sides with shorthand classes. It includes individual properties, all properties and vertical and horizontal properties.

It classes are built from a default Sass map ranging from .25rem to 3rem.

Notation

The spacing utilities that apply to all breakpoints, from xs to xl, don’t have breakpoint abbreviation in them. It?s because those classes are applied from min-width: 0 and up, and 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.

Here, “property” is one of the following:

• m – It is used for classes that set margin
• p – It is used for classes that set padding

“sides” is one of the following:

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

“size” is one of the following:

• 0 – It is used for classes that eliminate the margin or padding by setting it to 0
• 1 – (By default) It is used for classes that set the margin or padding to $spacer-x * .25 or $spacer-y * .25
• 2 – (by default) It is used for classes that set the margin or padding to $spacer-x * .5 or $spacer-y * .5
• 3 – (by default) It is used for classes that set the margin or padding to $spacer-x or $spacer-y
• 4 – (by default) It is used for classes that set the margin or padding to $spacer-x * 1.5 or $spacer-y * 1.5
• 5 – (by default) It is used for classes that set the margin or padding to $spacer-x * 3 or $spacer-y * 3

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

Example

Let’s take an example to see usage of these classes:

.mt-0 {  

  margin-top: 0 !important;  

}  

  

.ml-1 {  

  margin-left: ($spacer-x * .25) !important;  

}  

  

.px-2 {  

  padding-left: ($spacer-x * .5) !important;  

  padding-right: ($spacer-x * .5) !important;  

}  

  

.p-3 {  

  padding: $spacer-y $spacer-x !important;  

} 

Horizontal centering

Bootstrap also supports .mx-auto class for horizontally centering fixed-width block level content. Content that has display: block and a width set?by setting the horizontal margins to auto.

<div class="mx-auto" style="width: 200px;">  

  Centered element  

</div>