当flex-direction为'column'时，CSS flex-basis无法正常工作

Question

My goal is to create a two-column layout with flexbox wherein the first column has two rows and the second column has one, like this:

Setting flex-basis: 100% on the third item gives the desired effect, but only when the container's flex-direction is row :

Changing flex-direction to column results in the following, unless the height is set explicitly, which is infeasible in my project:

How can I get the first image without explicitly setting the height of the container?

Here's a Plunker illustrating the problem .

 body { display: flex; height: 100px; width: 100px; } .container { display: flex; flex-direction: column; /* Setting this to `row` gives the expected effect,but rotated */ flex-grow: 1; flex-wrap: wrap; /* height: 100%; */ /* Setting this fixes the problem, but is infeasible for my project*/ } .item { flex-grow: 1; } .one { background-color: red; } .two { background-color: blue; } .three { background-color: green; flex-basis: 100%; } 

 <div class="container"> <div class="item one">&nbsp;</div> <div class="item two">&nbsp;</div> <div class="item three">&nbsp;</div> </div> 

Answer 1

Why it doesn't work :

Flex wrap only happens when the initial main size of the flex items overflows the flex container. In the case of flex-direction: row , this is when they flex items are wider than the container. With flex-direction: column , they must overflow the height of the container.

But in CSS, height behaves fundamentally differently than width. The height of a container in CSS is determined by the height of its children. Thus, without something constraining the container's height, they flex items will never overflow; they just make their container taller. If they don't overflow, they won't wrap.

Possible solutions :

You have to constrain the height of the container. The obvious way (which you said is off the table), is setting an explicit height or max-height .

Ask yourself why you need to constrain the height. Is it to stay within the viewport? You could use viewport-relative units and set something like max-height: 100vh . Is it to equal the height of another column outside this flex container? You might be able to constrain it with another flexbox. Make this flex container a flex item in an outer flexbox. Something else in that outer flexbox would have to establish its height, though.

Answer 2

Try to set flex: none for blocks inside the container in the condition when you change the orientation ( @media etc.)

I tested it in Chrome and Firefox.

Answer 3

As far as i understand, the following code give the result you want:

body {
  display: flex;
  height: 100px;
  width: 100px;
}

.container {
  display: flex;
  flex-direction: column; 
  flex-wrap: wrap;
  flex-grow:1;
}

.item {
  flex-basis:50%;
}

.one {
  background-color: red;
}

.two {
  background-color: blue;

}

.three {
  background-color: green;
  flex-basis:100%;
}

Except from the flex-basis:50%; this code is equal to the code you use in the plunker. For some reason the plunker does not support flex-basis , see also:

Answer 4

I think you should build your layout using a Grid System in mind. On your first picture we can see 2 cols: first col is red and blue boxes, second col is the green box.

And then the structure should be like this:

<div class="flex-container">
    <div class="col column">
        <div class="content red"></div>
        <div class="content blue"></div>
    </div>
    <div class="col">
        <div class="content green"></div>
    </div>
</div>

Using these styles:

.flex-container {
   display:flex;
}
.col {
   flex:1;
   display:flex;
}
.column {
   flex-direction:column;
}
.content {
   flex:1;
}

Here is a quick code using your demo goal: https://jsfiddle.net/wyyLvymL/ Hope it helps! (if you need to understand how does it works, ping me)