Html – CSS height issue with flex box inside flex box

cssflexboxgoogle-chromehtml

I am having a problem with flex boxes contained inside flex boxes. The JS Fiddle at http://jsfiddle.net/fr077nn2/ contains the following code:

    #container{
      position: absolute;
      height: 100%;
      width: 100%;
      border: 3px solid yellow;
    }
    .app {
      display: flex;
      flex-direction: column;
      height: 100%;
      border: 3px solid black;
    }
    .app-header {
      border: 3px solid red;
    }
    .app-content {
      border: 3px solid green;
      flex: 1;
      overflow: hidden;
    }
    .app-footer {
      border: 3px solid blue;
    }

   <div id="container">
      <div class="app">
        <div class="app-header">HEADER1</div>
        <div class="app-content">
          <div class="app">
            <div class="app-header">HEADER2</div>
            <div class="app-content">CONTENT2</div>
            <div class="app-footer">FOOTER2</div>
          </div>
        </div>
        <div class="app-footer">FOOTER1</div>
      </div>
    </div>

I am trying to get the .app-content DIVs fill up the remaining space of the parent .app DIV. It works well for the outer boxes, as shown in the fiddle. However, for the inner boxes, CONTENT2 is not filling the remaining space. I suspect that height:100% does not work in that case because the height of the parent DIV is not properly known… any suggestion how to achieve the above properly?

Edit: Works fine on Firefox as expected not on Chrome.

Best Answer

Generally speaking, 100% height works when the parent has a well defined height. In your example, the outermost app-content does not have an explicit height which is why 100% height on its child does not work.

A simple workaround is to use relative-absolute positioning to size the child:

#container {
  position: absolute;
  height: 100%;
  width: 100%;
  border: 3px solid yellow;
}
.app {
  display: flex;
  flex-direction: column;
  height: 100%;
  border: 3px solid black;
}
.app-header {
  border: 3px solid red;
}
.app-content {
  border: 3px solid green;
  flex: 1;
  /* added property */
  position: relative;
}
.app-footer {
  border: 3px solid blue;
}
/* added rule */
.app-content > .app {
  height: auto;
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
}
/* scrollbar and border correction */
body {
  margin: 0;
  padding: 0;
}
div {
  box-sizing: border-box;
}

<div id="container">
  <div class="app">
    <div class="app-header">HEADER1</div>
    <div class="app-content">
      <div class="app">
        <div class="app-header">HEADER2</div>
        <div class="app-content">CONTENT2</div>
        <div class="app-footer">FOOTER2</div>
      </div>
    </div>
    <div class="app-footer">FOOTER1</div>
  </div>
</div>

2015 update: the flexbox approach

There are two other answers briefly mentioning flexbox; however, that was more than two years ago, and they don't provide any examples. The specification for flexbox has definitely settled now.

Note: Though CSS Flexible Boxes Layout specification is at the Candidate Recommendation stage, not all browsers have implemented it. WebKit implementation must be prefixed with -webkit-; Internet Explorer implements an old version of the spec, prefixed with -ms-; Opera 12.10 implements the latest version of the spec, unprefixed. See the compatibility table on each property for an up-to-date compatibility status.

(taken from https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Flexible_boxes)

All major browsers and IE11+ support Flexbox. For IE 10 or older, you can use the FlexieJS shim.

To check current support you can also see here: http://caniuse.com/#feat=flexbox

Working example

With flexbox you can easily switch between any of your rows or columns either having fixed dimensions, content-sized dimensions or remaining-space dimensions. In my example I have set the header to snap to its content (as per the OPs question), I've added a footer to show how to add a fixed-height region and then set the content area to fill up the remaining space.

html,
body {
  height: 100%;
  margin: 0;
}

.box {
  display: flex;
  flex-flow: column;
  height: 100%;
}

.box .row {
  border: 1px dotted grey;
}

.box .row.header {
  flex: 0 1 auto;
  /* The above is shorthand for:
  flex-grow: 0,
  flex-shrink: 1,
  flex-basis: auto
  */
}

.box .row.content {
  flex: 1 1 auto;
}

.box .row.footer {
  flex: 0 1 40px;
}

<!-- Obviously, you could use HTML5 tags like `header`, `footer` and `section` -->

<div class="box">
  <div class="row header">
    <p><b>header</b>
      <br />
      <br />(sized to content)</p>
  </div>
  <div class="row content">
    <p>
      <b>content</b>
      (fills remaining space)
    </p>
  </div>
  <div class="row footer">
    <p><b>footer</b> (fixed height)</p>
  </div>
</div>

In the CSS above, the flex property shorthands the flex-grow, flex-shrink, and flex-basis properties to establish the flexibility of the flex items. Mozilla has a good introduction to the flexible boxes model.

CSS 100% height with padding/margin

I learned how to do these sort of things reading "PRO HTML and CSS Design Patterns". The display:block is the default display value for the div, but I like to make it explicit. The container has to be the right type; position attribute is fixed, relative, or absolute.

.stretchedToMargin {
  display: block;
  position:absolute;
  height:auto;
  bottom:0;
  top:0;
  left:0;
  right:0;
  margin-top:20px;
  margin-bottom:20px;
  margin-right:80px;
  margin-left:80px;
  background-color: green;
}

<div class="stretchedToMargin">
  Hello, world
</div>

Fiddle by Nooshu's comment

Best Answer

Related Solutions

Html – Make a div fill the height of the remaining screen space

2015 update: the flexbox approach

Working example

CSS 100% height with padding/margin

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