This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
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.
/* <length> values */ block-size: 300px; block-size: 25em; /* <percentage> values */ block-size: 75%; /* Keyword values */ block-size: 25em border-box; block-size: 75% content-box; block-size: max-content; block-size: min-content; block-size: available; block-size: fit-content; 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.
| Initial value | auto |
|---|---|
| Applies to | same as width and height
|
| Inherited | no |
| Percentages | block-size of containing block |
| Media | visual |
| Computed value | same as width and height
|
| Animation type | discrete |
| Canonical order | the unique non-ambiguous order defined by the formal grammar |
The block-size property takes the same values as the width and height properties.
<'width'>
<p class="exampleText">Example text</p>
.exampleText {
writing-mode: vertical-rl;
background-color: yellow;
block-size: 200px;
} | Specification | Status | Comment |
|---|---|---|
| CSS Logical Properties and Values Level 1 The definition of 'block-size' in that specification. | Editor's Draft | Initial definition |
| Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic support | No | ? |
41 38 — 511 |
No | No | No |
| Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
|---|---|---|---|---|---|---|---|
| Basic support | No | ? | ? |
41 38 — 511 |
No | No | ? |
1. From version 38 until version 51 (exclusive): this feature is behind the layout.css.vertical-text.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
width and height
writing-mode
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https://developer.mozilla.org/en-US/docs/Web/CSS/block-size