flex-basis

  • Revision slug: CSS/flex-basis
  • Revision title: flex-basis
  • Revision id: 317069
  • Created:
  • Creator: teoli
  • Is current revision? No
  • Comment

Revision Content

{{ CSSRef() }}

Summary

The flex-basis CSS property specifies the flex basis which is the initial main size of a flex item.

  • {{ Xref_cssinitial() }}auto
  • Applies to flex items
  • {{ Xref_cssinherited() }} no
  • Media {{ Xref_cssvisual() }}
  • {{ Xref_csscomputed() }}as specified, with lengths made absolute

See Using CSS flexible boxes for more properties and information.

Syntax

Formal syntax: <'width'>
flex-basis: value

flex-basis: inherit

Values

percentage
Computed value returns a percentage of the parent flex container main size property. Negative values are invalid.
absolute length
Defined as a number followed by a absolute unit such as px, mm or pt. Negative values are invalid.
initial
Refers to the default value of the property.
auto
The computed value of flex-basis equals the computed value of the main size of the flex item.
Note: Writing Modes Level 3 specification will introduce the following new keywords: min-content, max-content, fill-available and fit-content.
Note: flex-basis determines the size of the content-box unless specified otherwise using {{ Cssxref("box-sizing") }}.

Examples

element { 
  flex-basis: 18em;
}

Specifications

Specification Status Comment
{{ SpecName('CSS3 Flexbox', '#flex-basis', 'flex-basis') }} {{ Spec2('CSS3 Flexbox') }}  

Browser compatibility

{{ CompatibilityTable() }}

Feature Firefox (Gecko) Chrome Internet Explorer Opera Safari
Basic support {{ CompatGeckoDesktop("18.0") }} (behind a pref) 21.0{{ property_prefix("-webkit") }} {{ CompatNo() }} {{ CompatNo() }} {{ CompatNo() }}
Feature Firefox Mobile (Gecko) Android IE Phone Opera Mobile Safari Mobile
Basic support {{ CompatUnknown() }} {{ CompatUnknown() }} {{ CompatNo() }} {{ CompatNo() }} {{ CompatNo() }}

See also

Revision Source

<p>{{ CSSRef() }}</p>
<h2 id="Summary">Summary</h2>
<p>The <code>flex-basis</code> <a href="/en-US/docs/CSS" title="CSS">CSS</a> property specifies the flex basis which is the initial <strong>main size</strong> of a flex item.</p>
<ul class="cssprop">
  <li><dfn>{{ Xref_cssinitial() }}</dfn><code>auto</code></li>
  <li><dfn>Applies to</dfn> flex items</li>
  <li><dfn>{{ Xref_cssinherited() }}</dfn> no</li>
  <li><dfn>Media</dfn> {{ Xref_cssvisual() }}</li>
  <li><dfn>{{ Xref_csscomputed() }}</dfn>as specified, with lengths made absolute</li>
</ul>
<p>See&nbsp;<a href="/en/CSS/Using_CSS_flexible_boxes" title="/en/CSS/Using_CSS_flexible_boxes">Using CSS flexible boxes</a>&nbsp;for more properties and information.</p>
<h2 id="Syntax">Syntax</h2>
<pre class="twopartsyntaxbox">
Formal syntax: &lt;'width'&gt;
</pre>
<pre>
flex-basis: <em>value</em>

flex-basis: inherit
</pre>
<h3 id="Values">Values</h3>
<dl>
  <dt>
    <code>percentage</code></dt>
  <dd>
    Computed value returns a percentage of the parent flex container main size property. Negative values are invalid.</dd>
  <dt>
    <code>absolute length</code></dt>
  <dd>
    Defined as a number followed by a absolute unit such as <code>px</code>, <code>mm</code> or <code>pt</code>. Negative values are invalid.</dd>
  <dt>
    <code>initial</code></dt>
  <dd>
    Refers to the default value of the property.</dd>
  <dt>
    <code>auto</code></dt>
  <dd>
    The computed value of <code>flex-basis</code> equals the computed value of the main size of the flex item.</dd>
</dl>
<div class="note">
  <strong>Note:</strong> Writing Modes Level 3 specification will introduce the following new keywords: <code>min-content</code>, <code>max-content</code>, <code>fill-available</code> and <code>fit-content</code>.</div>
<div class="note">
  <strong>Note:</strong> <code>flex-basis</code> determines the size of the content-box unless specified otherwise using {{ Cssxref("box-sizing") }}.</div>
<h2 id="Examples">Examples</h2>
<pre>
element { 
  flex-basis: 18em;
}
</pre>
<h2 id="Specifications">Specifications</h2>
<table class="standard-table">
  <thead>
    <tr>
      <th>Specification</th>
      <th>Status</th>
      <th>Comment</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>{{ SpecName('CSS3 Flexbox', '#flex-basis', 'flex-basis') }}</td>
      <td>{{ Spec2('CSS3 Flexbox') }}</td>
      <td>&nbsp;</td>
    </tr>
  </tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
<p>{{ CompatibilityTable() }}</p>
<div id="compat-desktop">
  <table class="compat-table">
    <tbody>
      <tr>
        <th>Feature</th>
        <th>Firefox (Gecko)</th>
        <th>Chrome</th>
        <th>Internet Explorer</th>
        <th>Opera</th>
        <th>Safari</th>
      </tr>
      <tr>
        <td>Basic support</td>
        <td>{{ CompatGeckoDesktop("18.0") }} (behind a pref)</td>
        <td>21.0{{ property_prefix("-webkit") }}</td>
        <td>{{ CompatNo() }}</td>
        <td>{{ CompatNo() }}</td>
        <td>{{ CompatNo() }}</td>
      </tr>
    </tbody>
  </table>
</div>
<div id="compat-mobile">
  <table class="compat-table">
    <tbody>
      <tr>
        <th>Feature</th>
        <th>Firefox Mobile (Gecko)</th>
        <th>Android</th>
        <th>IE&nbsp;Phone</th>
        <th>Opera Mobile</th>
        <th>Safari Mobile</th>
      </tr>
      <tr>
        <td>Basic support</td>
        <td>{{ CompatUnknown() }}</td>
        <td>{{ CompatUnknown() }}</td>
        <td>{{ CompatNo() }}</td>
        <td>{{ CompatNo() }}</td>
        <td>{{ CompatNo() }}</td>
      </tr>
    </tbody>
  </table>
</div>
<h2 id="See_also">See also</h2>
<ul>
  <li><a href="/en-US/docs/CSS/Using_CSS_flexible_boxes" title="/en-US/docs/CSS/Using_CSS_flexible_boxes">Using CSS flexible boxes</a></li>
  <li>{{ CSS_Reference:FlexBox() }}</li>
</ul>
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