block-size

The block-size CSS property defines the horizontal or vertical size of an element's block, depending on its writing mode. It corresponds to either the width or the height property, depending on the value of writing-mode.

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Syntax

/* <length> values */
block-size: 300px;
block-size: 25em;

/* <percentage> values */
block-size: 75%;

/* Keyword values */
block-size: max-content;
block-size: min-content;
block-size: fit-content(20em);
block-size: auto;

/* Global values */
block-size: inherit;
block-size: initial;
block-size: unset;

If the writing mode is vertically oriented, the value of block-size relates to the width of the element; otherwise, it relates to the height of the element. A related property is inline-size, which defines the other dimension of the element.

Syntax

Values

The block-size property takes the same values as the width and height properties.

Formal definition

Formal syntax

<'width'>

Examples

Block size with vertical text

HTML

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

CSS

.exampleText {
  writing-mode: vertical-rl;
  background-color: yellow;
  block-size: 200px;
}

Result

Specifications

Browser compatibility

See also

• The mapped physical properties: width and height
• writing-mode