css property

`margin-block-start` CSS property

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.

Interactive exampleOpen the canonical MDN source to run this embedded demo.

margin-block-start: 20px;
writing-mode: horizontal-tb;

margin-block-start: 20px;
writing-mode: vertical-rl;

margin-block-start: 20%;
writing-mode: horizontal-tb;

margin-block-start: auto;
writing-mode: vertical-lr;

<section id="default-example">
  <div id="container">
    <div class="row">One</div>
    <div class="row transition-all" id="example-element">Two</div>
    <div class="row">Three</div>
  </div>
</section>

#container {
  width: 300px;
  height: 200px;
  display: flex;
  align-content: flex-start;
  flex-direction: column;
  justify-content: flex-start;
}

.row {
  height: 33.33%;
  display: inline-block;
  border: solid #ce7777 10px;
  background-color: #2b3a55;
  color: white;
  flex-shrink: 0;
}

#example-element {
  border: solid 10px #ffbf00;
  background-color: #2b3a55;
}

Syntax

/* <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(--my-anchor 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-top property.

Formal definition

Formal syntax

Examples

Setting block start margin

HTML

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

CSS

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

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

Result

Interactive exampleOpen the canonical MDN source to run this embedded demo.

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.