Control width of flex items arranged vertically in a flex container - html

Question

I'm trying to achieve the effect where the boxes labeled "HALF", take up only 50% of the width (aka they share the first row evenly).
The base requirement is that they remain in a single container. Is this possible to achieve using flexbox?
I've tried playing around with flex-grow, flex-shrink, and flex-basis but I'm afraid I'm not understanding how to make it work, or if it's even possible, given the single container requirement.
Consider this fiddle: http://jsfiddle.net/GyXxT/270/
div {
border: 1px solid;
}
.container {
width: 400px;
display: flex;
flex-direction: column;
}
.child {
height: 200px;
}
.child.half {
flex: 1 1 10em;
color: green;
}
.child:not(.half) {
flex-shrink: 2;
flex-basis: 50%;
color: purple;
}
<div class="container">
<div class="child half">
HALF
</div>
<div class="child half">
HALF
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
</div>

Answer 1

Instead of flex-direction: column, you can try a wrapping flexbox using flex-wrap: wrap; and you can set:
flex-basis: 50% for the half width divs
flex-basis: 100% for the full width divs
See that I have thrown in box-sizing: border-box to adjust for the widths when using flex-basis.
See demo below:
div {
border: 1px solid;
box-sizing: border-box;
}
.container {
width: 400px;
display: flex;
flex-wrap: wrap;
}
.child {
height: 200px;
}
.child.half {
flex-basis: 50%;
color: green;
}
.child:not(.half) {
flex-basis: 100%;
color: purple;
}
<div class="container">
<div class="child half">
HALF
</div>
<div class="child half">
HALF
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
</div>

Answer 2

The flex sizing properties -- flex-grow, flex-shrink, flex-basis and flex -- work only along the main axis of the flex container.
Since your container is flex-direction: column, the main axis is vertical, and these properties are controlling height, not width.
For sizing flex items horizontally in a column-direction container you'll need the width property.
(Here's a more detailed explanation: What are the differences between flex-basis and width?)
To achieve your layout with a single container, see another answer to this question.
If you want to stay in column-direction, you'll need to wrap the .half elements in their own container.
.container {
display: flex;
flex-direction: column;
width: 400px;
}
.container > div:first-child {
display: flex;
}
.child.half {
flex: 1 1 10em;
color: green;
width: 50%;
}
.child {
height: 200px;
width: 100%;
border: 1px solid;
}
* {
box-sizing: border-box;
}
<div class="container">
<div><!-- nested flex container for half elements -->
<div class="child half">HALF</div>
<div class="child half">HALF</div>
</div>
<div class="child">FULL</div>
<div class="child">FULL</div>
<div class="child">FULL</div>
<div class="child">FULL</div>
</div>

Answer 3

The base requirement is that they remain in a single container.
That can also be done without flexbox, by simply float the 2 half elements
div {
border: 1px solid;
box-sizing: border-box;
}
.container {
width: 400px;
}
.child {
height: 200px;
}
.child.half {
float: left;
width: 50%;
color: green;
}
.child:not(.half) {
width: 100%;
color: purple;
}
<div class="container">
<div class="child half">
HALF
</div>
<div class="child half">
HALF
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
<div class="child">
FULL
</div>
</div>

Answer 4

If the purpose is to hardcode the size in CSS units, or in percentages (which was mentioned the question), #kukkuz's solution is good as it is.
If you want to size element widths according to their own individual contents, then align-tems: flex-start or similar could do the job. It's possible to deal with the dimension perpendicular to that of the flex layout itself. See a tester on the bottom of the doc page
(Old question, but previous answers were incomplete, some are misleading)