min-width

The element's width is set to the value of min-width whenever min-width is larger than max-width or width.

<length>

Defines the min-width as an absolute value.

<percentage>

Defines the min-width as a percentage of the containing block's width.

auto

The default value. The source of the automatic value for the specified element depends on its display value. For block boxes, inline boxes, inline blocks, and all table layout boxes auto resolves to 0.

For flex items and grid items, the minimum width value is either the specified suggested size, such as the value of the width property, the transferred size, calculated if the element has an aspect-ratio set and the height is a definite size, otherwise, the min-content size is used. If the flex or grid item is a scroll container, or if a grid item spans more than one flexible column track, the automatic minimum size is 0.

max-content

The intrinsic preferred min-width.

min-content

The intrinsic minimum min-width.

fit-content

Use the available space, but not more than max-content, i.e. min(max-content, max(min-content, stretch)).

fit-content(<length-percentage>)

Uses the fit-content formula with the available space replaced by the specified argument, i.e. min(max-content, max(min-content, argument)).

stretch

Limits the minimum width of the element's margin box to the width of its containing block. It attempts to make the margin box fill the available space in the containing block, so in a way behaving similar to 100% but applying the resulting size to the margin box rather than the box determined by box-sizing.

Note: To check aliases used by browsers for the stretch value and its implementation status, see the Browser compatibility section.

min-width = 
  auto                                      |
  <length-percentage [0,∞]>                 |
  min-content                               |
  max-content                               |
  fit-content( <length-percentage [0,∞]> )  |
  <calc-size()>                             |
  <anchor-size()>                           

<length-percentage> = 
  <length>      |
  <percentage>  

<calc-size()> = 
  calc-size( <calc-size-basis> , <calc-sum> )  

<anchor-size()> = 
  anchor-size( [ <anchor-name> || <anchor-size> ]? , <length-percentage>? )  

<calc-size-basis> = 
  <intrinsic-size-keyword>  |
  <calc-size()>             |
  any                       |
  <calc-sum>                

<calc-sum> = 
  <calc-product> [ [ '+' | '-' ] <calc-product> ]*  

<anchor-name> = 
  <dashed-ident>  

<anchor-size> = 
  width        |
  height       |
  block        |
  inline       |
  self-block   |
  self-inline  

<calc-product> = 
  <calc-value> [ [ '*' | '/' ] <calc-value> ]*  

<calc-value> = 
  <number>        |
  <dimension>     |
  <percentage>    |
  <calc-keyword>  |
  ( <calc-sum> )  

<calc-keyword> = 
  e          |
  pi         |
  infinity   |
  -infinity  |
  NaN        

• max-width
• width
• min-inline-size
• min-block-size
• box-sizing
• Introduction to the CSS basic box model
• CSS box model module