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


/* <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 */

/* 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.


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 = 


Setting block start margin


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


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

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



Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
margin-block-start 87 87 41 No 73 12.1 87 87 41 62 12.2 14.0

See also

© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.