firefox overflow-y not working with nested flexbox
CssFirefoxOverflowFlexboxCss Problem Overview
I have designed a 100% width 100% height layout with css3 flexbox, which works both on IE11 (and probably on IE10 if emulation of IE11 is correct).
But Firefox (35.0.1), overflow-y is not working. As you can see in this codepen : http://codepen.io/anon/pen/NPYVga
firefox is not rendering overflow correctly. It shows one scrollbar
html,
body {
height: 100%;
margin: 0;
padding: 0;
border: 0;
}
.level-0-container {
height: 100%;
display: -webkit-box;
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-webkit-box-orient: vertical;
-webkit-box-direction: normal;
-webkit-flex-direction: column;
-ms-flex-direction: column;
flex-direction: column;
}
.level-0-row1 {
border: 1px solid black;
box-sizing: border-box;
}
.level-0-row2 {
-webkit-box-flex: 1;
-webkit-flex: 1;
-ms-flex: 1;
flex: 1;
border: 1px solid black;
box-sizing: border-box;
display: -webkit-box;
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-webkit-box-orient: horizontal;
-webkit-box-direction: normal;
-webkit-flex-direction: row;
-ms-flex-direction: row;
flex-direction: row;
}
.level-1-col1 {
width: 20em;
overflow-y: auto;
}
.level-1-col2 {
-webkit-box-flex: 1;
-webkit-flex: 1;
-ms-flex: 1;
flex: 1;
border: 4px solid blue;
box-sizing: border-box;
display: -webkit-box;
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-webkit-box-orient: vertical;
-webkit-box-direction: normal;
-webkit-flex-direction: column;
-ms-flex-direction: column;
flex-direction: column;
}
.level-2-row2 {
-webkit-box-flex: 1;
-webkit-flex: 1;
-ms-flex: 1;
flex: 1;
border: 4px solid red;
box-sizing: border-box;
overflow-y: auto;
}
<html>
<body>
<div class="level-0-container">
<div class="level-0-row1">
Header text
</div>
<div class="level-0-row2">
<div class="level-1-col1">
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
line <br/>
</div>
<div class="level-1-col2">
<div class="level-2-row1">
Some text
<p/> Some text 2
<p/> Some text 3
<p/>
</div>
<div class="level-2-row2">
<p>some text</p>
<p>some text</p>
<p>some text</p>
<p>some text</p>
<p>some text</p>
<p>some test</p>
</div>
</div>
</div>
</div>
</body>
</html>
Css Solutions
Solution 1 - Css
tl;dr: you need min-height:0 in your .level-0-row2 rule. (Here's a codepen with that fix.)
More detailed explanation:
Flex items establish a default minimum size that's based on their children's intrinsic size (which doesn't consider "overflow" properties on their children/descendants).
Whenever you've got an element with overflow: [hidden|scroll|auto] inside of a flex item, you need to give its ancestor flex item min-width:0 (in a horizontal flex container) or min-height:0 (in a vertical flex container), to disable this min-sizing behavior, or else the flex item will refuse to shrink smaller than the child's min-content size.
See https://bugzilla.mozilla.org/show_bug.cgi?id=1043520 for more examples of sites that have been bitten by this. (Note that this is just a metabug to track sites that were broken by this sort of issue, after this spec-text was implemented -- it's not actually a bug in Firefox.)
You won't see this in Chrome (at least, not as of this posting) because they haven't implemented this minimum sizing behavior yet. (EDIT: Chrome has now implemented this min-sizing behavior, but they may still incorrectly collapse min-sizes to 0 in some cases.)
Solution 2 - Css
Recently I have found a better solution:
Instead of using:
flex:1 1 auto;
min-height: 0;
it's even better to use:
flex:1 1 0;
Basically this tells the browser to set the size of the element initially to 0 (so replacing min-height) and allow it to expand by a ratio of 1.
There is a really good video for explaining how flexbox works by Kevin Powell which I highly recommend to watch (https://www.youtube.com/watch?v=fm3dSg4cxRI) It explains in detail how flexbox algoritm works.