Команда flex в css

CSS Flexible Box Layout

Способ CSS раскладки Flexible Box (CSS Flexible Box Layout или Flexbox) — это способ CSS раскладки, означающий блочную модель CSS, оптимизированную для построения пользовательских интерфейсов. Во флекс-модели потомки флекс-контейнера могут выстраиваться в любом направлении (право/лево, верх/низ), растягиваться, заполняя свободное пространство, или сжиматься во избежание переполнения родительского контейнера. Доступно различное выравнивание потомков по горизонтали и вертикали. Комбинация из родительского и вложенных блоков позволяют создавать такой layout, при котором элементы автоматически выстраиваются в столбы или строки.

Базовый пример

В следующем примере контейнер объявлен как display: flex , таким образом его три потомка становятся флекс-элементами. Свойству justify-content присвоено значение space-between для того, чтобы, во-первых, задать между элементами равные интервалы по основной оси, и, во-вторых, «примагнитить» первый и последний элементы к левому и правому краям контейнера соответственно. Также можно заметить, что флекс-элементы растянуты перпендикулярно оси; это происходит из-за того, что дефолтным значением align-items является stretch . Так как высота родительского контейнера не задана, элементы растягиваются по высоте и принимают значение высоты самого высокого из них.

Reference

CSS Properties

Guides

Step-by-step tutorial about how to build layouts using this feature.

Tutorial explaining how to use flexbox in the specific context of Web applications.

Спецификации

Found a content problem with this page?

This page was last modified on 26 мая 2023 г. by MDN contributors.

Your blueprint for a better internet.

Источник

flex

Baseline is determined by this web feature being supported on the current and the previous major versions of major browsers.

The flex CSS shorthand property sets how a flex item will grow or shrink to fit the space available in its flex container.

Try it

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

/* Keyword values */ flex: auto; flex: initial; flex: none; /* One value, unitless number: flex-grow flex-basis is then equal to 0. */ flex: 2; /* One value, width/height: flex-basis */ flex: 10em; flex: 30%; flex: min-content; /* Two values: flex-grow | flex-basis */ flex: 1 30px; /* Two values: flex-grow | flex-shrink */ flex: 2 2; /* Three values: flex-grow | flex-shrink | flex-basis */ flex: 2 2 10%; /* Global values */ flex: inherit; flex: initial; flex: revert; flex: revert-layer; flex: unset; 

The flex property may be specified using one, two, or three values.

• One-value syntax: the value must be one of:
  • a valid value for : then the shorthand expands to flex: 1 0 .
  • a valid value for : then the shorthand expands to flex: 1 1 .
  • the keyword none or one of the global keywords.
  • The first value must be a valid value for flex-grow .
  • The second value must be one of:
    • a valid value for flex-shrink : then the shorthand expands to flex: 0 .
    • a valid value for flex-basis : then the shorthand expands to flex: 1 .
    1. a valid value for flex-grow .
    2. a valid value for flex-shrink .
    3. a valid value for flex-basis .

    Values

    The item is sized according to its width and height properties. It shrinks to its minimum size to fit the container, but does not grow to absorb any extra free space in the flex container. This is equivalent to setting » flex: 0 1 auto «.

    The item is sized according to its width and height properties, but grows to absorb any extra free space in the flex container, and shrinks to its minimum size to fit the container. This is equivalent to setting » flex: 1 1 auto «.

    The item is sized according to its width and height properties. It is fully inflexible: it neither shrinks nor grows in relation to the flex container. This is equivalent to setting » flex: 0 0 auto «.

    Defines the flex-grow of the flex item. Negative values are considered invalid. Defaults to 1 when omitted. (initial is 0 )

    Defines the flex-shrink of the flex item. Negative values are considered invalid. Defaults to 1 when omitted. (initial is 1 )

    Defines the flex-basis of the flex item. A preferred size of 0 must have a unit to avoid being interpreted as a flexibility. Defaults to 0 when omitted. (initial is auto )

    Description

    For most purposes, authors should set flex to one of the following values: auto , initial , none , or a positive unitless number. To see the effect of these values, try resizing the flex containers below:

    div class="flex-container"> div class="item auto">autodiv> div class="item auto">autodiv> div class="item auto">autodiv> div> div class="flex-container"> div class="item auto">autodiv> div class="item initial">initialdiv> div class="item initial">initialdiv> div> div class="flex-container"> div class="item auto">autodiv> div class="item auto">autodiv> div class="item none">nonediv> div> div class="flex-container"> div class="item initial">initialdiv> div class="item none">nonediv> div class="item none">nonediv> div> div class="flex-container"> div class="item four">4div> div class="item two">2div> div class="item one">1div> div> 

    *  box-sizing: border-box; > .flex-container  background-color: #f4f7f8; resize: horizontal; overflow: hidden; display: flex; margin: 1em; > .item  margin: 1em; padding: 0.5em; width: 110px; min-width: 0; background-color: #1b5385; color: white; font-family: monospace; font-size: 13px; > .initial  flex: initial; > .auto  flex: auto; > .none  flex: none; > .four  flex: 4; > .two  flex: 2; > .one  flex: 1; > 

    By default flex items don’t shrink below their minimum content size. To change this, set the item’s min-width or min-height .

    Formal definition

    • flex-grow : 0
    • flex-shrink : 1
    • flex-basis : auto
    • flex-grow : as specified
    • flex-shrink : as specified
    • flex-basis : as specified, but with relative lengths converted into absolute lengths
    • flex-grow : a number
    • flex-shrink : a number
    • flex-basis : a length, percentage or calc();

    Formal syntax

    Examples

    Setting flex: auto

    This example shows how a flex item with flex: auto grows to absorb any free space in the container.

    HTML

    div id="flex-container"> div id="flex-auto">flex: auto (click to toggle raw box)div> div id="flex-initial">flex: initialdiv> div> 

    CSS

    #flex-container  display: flex; font-family: Consolas, Arial, sans-serif; > #flex-container > div  padding: 1rem; > #flex-auto  flex: auto; border: 1px solid #f00; > #flex-initial  border: 1px solid #000; > 

    JavaScript

    const flexAuto = document.getElementById("flex-auto"); const flexInitial = document.getElementById("flex-initial"); flexAuto.addEventListener("click", () =>  flexInitial.style.display = flexInitial.style.display === "none" ? "block" : "none"; >); 

    Result

    The flex container contains two flex items:

    The «flex: initial» item takes up as much space as its width requires, but does not expand to take up any more space. All the remaining space is taken up by «flex: auto».

    When you click «flex: auto», we set «flex: initial»‘s display property to none , removing it from the layout. The «flex: auto» item then expands to occupy all the available space in the container.

    Specifications

    Browser compatibility

    BCD tables only load in the browser

    See also

    Found a content problem with this page?

    This page was last modified on Jul 17, 2023 by MDN contributors.

    Your blueprint for a better internet.

    MDN

    Support

    Our communities

    Developers

    Visit Mozilla Corporation’s not-for-profit parent, the Mozilla Foundation.
    Portions of this content are ©1998– 2023 by individual mozilla.org contributors. Content available under a Creative Commons license.

    Источник