min-block-size

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

* Some parts of this feature may have varying levels of support.

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

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

Try it

min-block-size: 150px;
writing-mode: horizontal-tb;

min-block-size: 150px;
writing-mode: vertical-rl;

min-block-size: 20px;
writing-mode: horizontal-tb;

min-block-size: 15em;
writing-mode: vertical-lr;


  
    This is a box where you can change the minimum block size. 
If there is
    more content than the minimum the box will grow in the block dimension as
    needed by the content.

#example-element {
  display: flex;
  flex-direction: column;
  background-color: #5b6dcd;
  justify-content: center;
  color: #ffffff;
}

Syntax

css

/*  values */
min-block-size: 100px;
min-block-size: 5em;
min-block-size: anchor-size(self-inline);

/*  values */
min-block-size: 10%;

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

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

Values

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

Formal definition

Initial value	`0`
Applies to	same as `width` and `height`
Inherited	no
Percentages	block-size of containing block
Computed value	same as `min-width` and `min-height`
Animation type	a length, percentage or calc();

Formal syntax

min-block-size = 
  <'min-width'>  

 = 
  auto                                      |
                   |
  min-content                               |
  max-content                               |
  fit-content(  )  |
                               |
                             

 = 
        |
    

 = 
  calc-size(  ,  )  

 = 
  anchor-size( [  ||  ]? , ? )  

 = 
    |
     |
  any             |
        

 = 
   [ [ '+' | '-' ]  ]*  

 = 
    

 = 
  width        |
  height       |
  block        |
  inline       |
  self-block   |
  self-inline  

 = 
   [ [ '*' | / ]  ]*  

 = 
          |
       |
      |
    |
  (  )  

 = 
  e          |
  pi         |
  infinity   |
  -infinity  |
  NaN

Examples

Setting minimum block size for vertical text

HTML

html

Example text

CSS

css

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

Result

Specifications

Specification
CSS Logical Properties and Values Level 1 # propdef-min-block-size
CSS Box Sizing Module Level 4 # sizing-values