margin-block-end

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Geoff Graham on

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The margin-block-end property in CSS defines the amount of space along the outer ending edge of an element in the block direction. It’s included in the CSS Logical Properties Level 1 specification, which is currently in Working Draft.

.element {
  margin-block-end: 25%;
  writing-mode: vertical-lr;
}

The ending edge in the block direction is determined by the element’s writing-mode, direction and text-orientation. So, when using margin-block-end in a horizontal left-to-right context, it acts just like margin-bottom as the starting edge of the element is the bottom of it.

But if we change the writing-mode to, say, vertical, the element is rotated, placing the ending edge toward the right As a result, margin-block-end behaves just like margin-right. Basically, the starting edge is relative to the direction it flows. That’s what we mean when talking about “logical” properties.

Syntax

margin-block-end: <‘margin-top’>

It’s kinda weird to see the syntax of one property reference the syntax of another CSS property right in the documentation, but that’s really what it is. What it’s basically trying to say is that the property accepts the same values as margin-top which follows this syntax:

margin-top: <length> | <percentage> | auto;
  • Initial value: 0
  • Applies to: all elements except internal table elements, ruby base containers, and ruby annotation containers
  • Inherited: no
  • Percentages: as for the corresponding physical property
  • Computed value: same as corresponding margin-* properties
  • Animation type: by computed value type

Values

margin-block-end accepts a single length or keyword value.

/* Length values */
margin-block-end: 20px;
margin-block-end: 2rem;
margin-block-end: 25%;

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

/* Global values */
margin-block-end: inherit;
margin-block-end: initial;
margin-block-end: unset;

Demo

Click the button in the following demo to see how the starting edge of the element changes with the writing-mode.

Browser support

IEEdgeFirefoxChromeSafariOpera
No79+41+69+12.1+56+
Android ChromeAndroid FirefoxAndroid BrowseriOS SafariOpera Mobile
YesYes81+12.2+59+
Source: caniuse

Further reading