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A propriedade max-width do CSS estabelece a largura máxima de um elemento. Ele previne o valor usado da propriedade width de se tornar maior que o valor indicado pelo max-width.

max-width substitui width, mas min-width substitui max-width.

Sintaxe

/* <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;
max-width: fill-available;

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

Valores

<length>
A largura máxima, expressada como <length>.
<percentage>
A largura máxima, expressada como <percentage> da largura contida do bloco.

Keyword values

none
A largura não possui valor máximo. (padrão)
max-content
A largura intríseca preferida.
min-content
A largura intríseca mínima preferida.
fill-available
A largura contida do bloco sem o margin, border e padding horizontal. (Note que alguns navegadores implementaram um nome antigo para essa keyword, available.)
fit-content
O mesmo que max-content.

Sintaxe formal

<length> | <percentage> | none | max-content | min-content | fit-content | fill-available

Exemplos

Neste exemplo, a cada "child" terá 150 pixels de largura ou comprimento do "parent," não importa qual é menor:

<div id="parent">
  <div id="child">
    Fusce pulvinar vestibulum eros, sed luctus ex lobortis quis.
  </div>
</div>
#parent {
  background: lightblue;
  width: 300px;
}

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

O valor de fit-content pode ser usado para atribuir o comprimento de um elemento no tamanho intrínseco necessário pelo seu conteúdo:

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

#child  {
  background: gold;
  width: 100%;
  max-width: -moz-fit-content;
  max-width: -webkit-fit-content;
}

Preocupações de acessibilidade

Garantir que os elementos atribuidos com max-width não estejam cortados e/ou não obscureça outro conteúdo quando a página é ampliada para aumentar o tamanho do texto. 

Especificações

Especificação Status Comentário
CSS Intrinsic & Extrinsic Sizing Module Level 3
The definition of 'max-width' in that specification.
Rascunho atual Adiciona o max-content, min-content, fit-content, e fill-available keywords. (Ambos CSS3 Box e CSS3 Writing Modes são rascunhos usados para definir essas keywords, mas foram substituídas por essa especificação.)
CSS Transitions
The definition of 'max-width' in that specification.
Rascunho atual Define max-width como animável.
CSS Level 2 (Revision 1)
The definition of 'max-width' in that specification.
Recomendação Definição inicial.

Initial valuenone
Aplica-se aall elements but non-replaced inline elements, table rows, and row groups
Inheritednão
Percentagesrefer to the width of the containing block
Midiavisual
Computed valuethe percentage as specified or the absolute length or none
Animation typea length, percentage or calc();
Canonical orderthe unique non-ambiguous order defined by the formal grammar

Compatibilidade com navegador

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
max-widthChrome Full support 1Edge Full support 12Firefox Full support 1
Notes
Full support 1
Notes
Notes CSS 2.1 leaves the behavior of max-width with table undefined. Firefox supports applying max-width to table elements.
IE Full support 7Opera Full support 4
Notes
Full support 4
Notes
Notes CSS 2.1 leaves the behavior of max-width with table undefined. Opera supports applying max-width to table elements.
Safari Full support 1WebView Android Full support 37Chrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 4
Notes
Full support 4
Notes
Notes CSS 2.1 leaves the behavior of max-width with table undefined. Firefox supports applying max-width to table elements.
Opera Android Full support YesSafari iOS Full support 1Samsung Internet Android ?
fit-content
Experimental
Chrome Full support 46
Full support 46
Full support 25
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Edge No support NoFirefox Partial support 3
Prefixed Notes
Partial support 3
Prefixed Notes
Prefixed Implemented with the vendor prefix: -moz-
Notes Firefox implements the definitions given in CSS3 Basic Box. This defines available and not fit-available. Also, the definition of fit-content is simpler than in CSS3 Sizing.
IE No support NoOpera Full support 44Safari Full support 6.1
Prefixed
Full support 6.1
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Full support 2
Alternate Name
Alternate Name Uses the non-standard name: intrinsic
WebView Android Full support 46
Full support 46
Full support Yes
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Chrome Android Full support 46Edge Mobile No support NoFirefox Android Partial support 4
Prefixed Notes
Partial support 4
Prefixed Notes
Prefixed Implemented with the vendor prefix: -moz-
Notes Firefox implements the definitions given in CSS3 Basic Box. This defines available and not fit-available. Also, the definition of fit-content is simpler than in CSS3 Sizing.
Opera Android Full support 43Safari iOS ? Samsung Internet Android Full support 5.0
max-content
Experimental
Chrome Full support 46
Full support 46
Full support 22
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Edge No support NoFirefox Full support 66
Full support 66
Full support 3
Prefixed
Prefixed Implemented with the vendor prefix: -moz-
IE No support NoOpera Full support 44Safari Full support 6.1
Prefixed
Full support 6.1
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Full support 2
Alternate Name
Alternate Name Uses the non-standard name: intrinsic
WebView Android Full support 46
Full support 46
Full support Yes
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Chrome Android Full support 46Edge Mobile No support NoFirefox Android Full support 66
Full support 66
Full support 4
Prefixed
Prefixed Implemented with the vendor prefix: -moz-
Opera Android Full support 43Safari iOS ? Samsung Internet Android Full support 5.0
min-content
Experimental
Chrome Full support 46
Full support 46
Full support 25
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Edge No support NoFirefox Full support 66
Full support 66
Full support 3
Prefixed
Prefixed Implemented with the vendor prefix: -moz-
IE No support NoOpera Full support 44Safari Full support 6.1
Prefixed
Full support 6.1
Prefixed
Prefixed Implemented with the vendor prefix: -webkit-
Full support 2
Alternate Name
Alternate Name Uses the non-standard name: intrinsic
WebView Android Full support 46Chrome Android Full support 46Edge Mobile No support NoFirefox Android Full support 66
Full support 66
Full support 4
Prefixed
Prefixed Implemented with the vendor prefix: -moz-
Opera Android Full support 43Safari iOS ? Samsung Internet Android Full support 5.0
stretch
Experimental
Chrome Full support 22
Alternate Name
Full support 22
Alternate Name
Alternate Name Uses the non-standard name: -webkit-fill-available
Edge No support NoFirefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support 4.4
Alternate Name
Full support 4.4
Alternate Name
Alternate Name Uses the non-standard name: -webkit-fill-available
Chrome Android Full support 25
Alternate Name
Full support 25
Alternate Name
Alternate Name Uses the non-standard name: -webkit-fill-available
Edge Mobile ? Firefox Android No support NoOpera Android ? Safari iOS ? Samsung Internet Android No support No

Legend

Full support  
Full support
Partial support  
Partial support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
See implementation notes.
See implementation notes.
Uses a non-standard name.
Uses a non-standard name.
Requires a vendor prefix or different name for use.
Requires a vendor prefix or different name for use.

Veja também

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