margin-trim

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

Syntax

margin-trim: none;
margin-trim: in-flow;
margin-trim: all;

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

Values

none
Margins are not trimmed by the container.
in-flow

For in-flow boxes contained by this box, block-axis margins adjacent to the box's edges are truncated to zero.

It also truncates any margins collapsed with such a margin.

all
Trims the margins of in-flow boxes and floats whose margins coincide with the container's content edge.

Formal definition

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

Formal syntax

none | in-flow | all

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:

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;
}

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:

span:last-child {
  margin-right: 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:

 article {
  margin-trim: in-flow;
  ...
}

Specifications

Specification Status
CSS Box Model Module Level 4
The definition of 'margin-trim' in that specification.
Editor's Draft

Browser compatibility

BCD tables only load in the browser

See also