margin-block-start

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2021.

The margin-block-start CSS property defines the logical block start margin of an element, which maps to a physical margin depending on the element's writing mode, directionality, and text orientation.

Try it

Syntax

css

/* <length> values */
margin-block-start: 10px; /* An absolute length */
margin-block-start: 1em; /* relative to the text size */
margin-block-start: 5%; /* relative to the nearest block container's width */
margin-block-start: anchor-size(width);
margin-block-start: calc(anchor-size(--myAnchor block, 20px) / 3);

/* Keyword values */
margin-block-start: auto;

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

It corresponds to the margin-top, margin-right, margin-bottom, or margin-left property depending on the values defined for writing-mode, direction, and text-orientation.

It relates to margin-block-end, margin-inline-start, and margin-inline-end, which define the other margins of the element.

Values

The margin-block-start property takes the same values as the margin-left property.

Formal definition

Initial value	`0`
Applies to	same as `margin`
Inherited	no
Percentages	depends on layout model
Computed value	if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, `auto`
Animation type	a length

Formal syntax

margin-block-start = 
  <'margin-top'>  

<margin-top> = 
  <length-percentage>  |
  auto                 |
  <anchor-size()>      

<length-percentage> = 
  <length>      |
  <percentage>  

<anchor-size()> = 
  anchor-size( [ <anchor-name> || <anchor-size> ]? , <length-percentage>? )  

<anchor-name> = 
  <dashed-ident>  

<anchor-size> = 
  width        |
  height       |
  block        |
  inline       |
  self-block   |
  self-inline

Examples

Setting block start margin

HTML

html

<div>
  <p class="exampleText">Example text</p>
</div>

CSS

css

div {
  background-color: yellow;
  width: 120px;
  height: 120px;
}

.exampleText {
  writing-mode: vertical-lr;
  margin-block-start: 20px;
  background-color: #c8c800;
}

Result

Specifications

Specification
CSS Logical Properties and Values Level 1 # margin-properties

Browser compatibility

BCD tables only load in the browser