max-width

The max-width CSS property sets the maximum width of an element. It prevents the used value of the width property from becoming larger than the value specified by max-width.

max-width overrides width, but min-width overrides max-width.

Syntax

/* <length> value */
max-width: 3.5em;

/* <percentage> value */
max-width: 75%;

/* Keyword values */
max-width: none;
max-width: max-content;
max-width: min-content;
max-width: fit-content(20em);

/* Global values */
max-width: inherit;
max-width: initial;
max-width: revert;
max-width: revert-layer;
max-width: unset;

Values

<length>: Defines the max-width as an absolute value.
<percentage>: Defines the max-width as a percentage of the containing block's width.
none: No limit on the size of the box.
max-content: The intrinsic preferred max-width.
min-content: The intrinsic minimum max-width.
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)).

Accessibility concerns

Ensure that elements set with a max-width are not truncated and/or do not obscure other content when the page is zoomed to increase text size.

Formal definition

Initial value	none
Applies to	all elements that accept width or height
Inherited	no
Computed value	as specified, with <length-percentage> values computed
Animation type	by computed value, recursing into fit-content()

Formal syntax

none | <length-percentage [0,∞]> | min-content | max-content | fit-content(<length-percentage [0,∞]>)

Examples

Setting max width in pixels

In this example, the "child" will be either 150 pixels wide or the width of the "parent," whichever is smaller.

HTML

<div id="parent">
  <div id="child">
    Fusce pulvinar vestibulum eros, sed luctus ex lobortis quis.
  </div>
</div>

CSS

#parent {
  background: lightblue;
  width: 300px;
}

#child {
  background: gold;
  width: 100%;
  max-width: 150px;
}

css properties max-width