margin-trim

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The margin-trim property allows the container to trim the margins of its children where they adjoin the container's edges.

Syntax

css
margin-trim: none;
margin-trim: block;
margin-trim: block-start;
margin-trim: block-end;
margin-trim: inline;
margin-trim: inline-start;
margin-trim: inline-end;

/* Global values */
margin-trim: inherit;
margin-trim: initial;
margin-trim: revert;
margin-trim: revert-layer;
margin-trim: unset;

Values

none

Margins are not trimmed by the container.

block

Margins provided to the block children where they adjoin the container's edges are trimmed to zero without affecting the margins provided to the container.

block-start

Margin of the first block child with the container's edge is trimmed to zero.

block-end

Margin of last block child with the container's edge is trimmed to zero.

inline

Margins provided to the inline children where they adjoin the container's edges are trimmed to zero, without affecting the spacing at the beginning and end of the row.

inline-start

Margin between the container's edge and the first inline child is trimmed to zero.

inline-end

Margin between the container's edge and the last inline child is trimmed to zero.

Formal definition

Initial valuenone
Applies toBlock containers and multi-column containers. It also applies to ::first-letter.
Inheritedno
Computed valueas specified
Animation typediscrete

Formal syntax

margin-trim = 
none |
[ block || inline ] |
[ block-start || inline-start || block-end || inline-end ]

Examples

Basic usage

Once support is implemented for this property, it will probably work like so:

When you've got a container with some inline children and you want to put a margin between each child but not have it interfere with the spacing at the end of the row, you might do something like this:

css
article {
  background-color: red;
  margin: 20px;
  padding: 20px;
  display: inline-block;
}

article > span {
  background-color: black;
  color: white;
  text-align: center;
  padding: 10px;
  margin-right: 20px;
  margin-left: 30px;
}

The problem here is that you'd end up with 20px too much spacing at the right of the row, so you'd maybe do this to fix it:

css
span:last-child {
  margin-right: 0;
  margin-left: 0;
}

It is a pain having to write another rule to achieve this, and it is also not very flexible. Instead, margin-trim could fix it:

css
article {
  margin-trim: inline-end;
  /* … */
}

Similarly, to remove left margin with the container's edge:

css
article {
  margin-trim: inline-start;
  /* … */
}

Specifications

Specification
CSS Box Model Module Level 4
# margin-trim

Browser compatibility

BCD tables only load in the browser

See also