A widthpropriedade em CSS especifica a largura da área de conteúdo do elemento. Essa área de “conteúdo” é a parte dentro do preenchimento, borda e margem de um elemento (o modelo de caixa).
.element ( width: 80%; )
No exemplo acima, os elementos que têm um nome de classe de .wrapterão 80% da largura de seu elemento pai. Os valores aceitos são qualquer um dos valores de comprimento, além de algumas palavras-chave que abordaremos mais tarde.
A largura pode ser substituída pelas propriedades estreitamente correlacionadas min-width e max-width.
.wrapper-1 ( width: 100%; max-width: 320px; /* Will be AT MOST 320px wide */ ) .wrapper-2 ( width: 100%; min-width: 20em; /* Will be AT LEAST 20em wide */ )
Indo mais fundo
Ao usar porcentagem (%) para largura, os autores devem estar cientes de que a porcentagem é baseada no pai do elemento, ou seja, na largura do bloco que o contém. Se o seu pai / mãe está configurado em 480px - conforme demonstrado por nossa demonstração - então a porcentagem é baseada nesse valor. Portanto, em nosso caso, 50% de 480px nos deixa com 240px como um valor de pixel calculado.
Observe que widthse aplica a todos os elementos, exceto elementos não substituídos ou embutidos, linhas da tabela e grupos de linhas (ou seja thead, tfoote tbody). Parece haver uma pequena incompatibilidade no que diz respeito à forma como o HTML define os elementos não substituídos e como o CSS os define, mas estamos nos referindo a ele da mesma forma que o CSS: elementos cujo conteúdo não é definido pela própria tag, como umCodePen Embed Fallback
Keyword values
With some special keyword values, it is possible to define width (and/or height) according to the content of the element.
min-content
The min-content value is the smallest measure that would fit around its content if all soft wrap opportunities within the box were taken.
The best example for this kind of value is a properly written figure element:
What a lovely kitten we got there in this image which is encapsulated in a figure element. How dear, look how long this caption is!
Once we have applied some basic styles to this markup, we get:
If we wanted that figure element to essentially be the size of that image, so the text wraps at the edges of the image. We could float it left or right, because float will exhibit that same kind of shrink-to-fit behavior, but what if we wanted to center it? min-content allows us to center it:
Because we’ve assigned min-content to the figure element, it takes the minimum width it can have when taking all soft wrap opportunities (like spaces between words) so that the content still fits in the box.
max-content
The max-content property refers to the narrowest measure a box could take while fitting around its content - if no soft wrap opportunities within the element were taken.
Check out what happens if we apply this to our simple kitten/figure demo:
Because the caption is very longer than the image is wide (it doesn’t take any soft wrap opportunity, like the spaces between words), it means it has to display the caption on a single line, thus the figure is as wide as that line.
fill-available
???. One of life’s great mysteries.
fit-content
The fit-content value is roughly equivalent to margin-left: auto and margin-right: auto in behaviour, except it works for unknown widths.
For instance, let’s say we need to center an inline navigation across the page. Your best bet would be to apply text-align: center to the ul, and display: inline-block to the li. This would give you something like this:
However, the blue background (from the ul element) spreads across the entire document because the ul is a block-level element, which means its width is restricted only by its containing element. What if we want to have the blue background collapsing around the list items? fit-content to the rescue!
With fit-content and margin: 1em auto, this works like a charm and only the navigation has a colored background, not the whole document width.
If you’re into this sort of thing, you’ll be happy to know the formula to define the size of a fit-content length is:
CodePen Embed Fallback