Web/CSS/margin-trim

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

Syntax

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 value	`none`
Applies to	Block containers and multi-column containers. It also applies to `::first-letter` and `::first-line`.
Inherited	no
Computed value	as specified
Animation type	discrete

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 4The definition of 'margin-trim' in that specification.	Editor's Draft

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`margin-trim` Experimental'	Chrome No support No	Edge No support No	Firefox No support No Notes' No support No Notes' Notes' See bug 1506241.	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android No support No Notes' No support No Notes' Notes' See bug 1506241.	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No

Legend

No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
See implementation notes.': See implementation notes.