I have a "weird" combination of flex columns.
The first has a fixed width and sticks to the top while scrolling down.
The second has only a max-width and is very tall.
The Third has flex: 1, to use the remaining space and also sticks to the top while scrolling down.
My problem is the 3rd one sometimes disapears (goes to the bottoom) depending on the size of the second one.
this is my simplified code:
.first {
width: 250px;
}
.third {
flex: 1;
}
.roundedBox {
background-color: aliceblue;
border-radius: 15px;
padding: 20px;
margin: 20px;
}
.grid-container {
display: flex;
flex-direction: row;
flex-wrap: wrap;
align-items: flex-start;
}
.sticky {
position: sticky;
top: 10px;
}
.item-long {
background: orchid;
height: 200vh;
}
<div class="grid-container">
<div class="first sticky roundedBox">Some content</div>
<div class="roundedBox item-long ">Lorem ipsum dolor </div>
<div class="third sticky roundedBox">Somecontent</div>
</div>
The real code can be seen here https://github.com/sergiosaint/Finance and the live demo here https://amortizacoes.netlify.app/
this image shows the problem appearing https://imgur.com/CAf7ovM
Related
Imagine the following layout, where the dots represent the space between the boxes:
[Left box]......[Center box]......[Right box]
When I remove the right box, I like the center box to still be in the center, like so:
[Left box]......[Center box].................
The same goes for if I would remove the left box.
................[Center box].................
Now when the content within the center box gets longer, it will take up as much available space as needed while remaining centered. The left and right box will never shrink and thus when where is no space left the overflow:hidden and text-overflow: ellipsis will come in effect to break the content;
[Left box][Center boxxxxxxxxxxxxx][Right box]
All the above is my ideal situation, but I have no idea how to accomplish this effect. Because when I create a flex structure like so:
.parent {
display : flex; // flex box
justify-content : space-between; // horizontal alignment
align-content : center; // vertical alignment
}
If the left and right box would be exactly the same size, I get the desired effect. However when one of the two is from a different size the centered box is not truly centered anymore.
Is there anyone that can help me?
Update
A justify-self would be nice, this would be ideal:
.leftBox {
justify-self : flex-start;
}
.rightBox {
justify-self : flex-end;
}
If the left and right boxes would be exactly the same size, I get the desired effect. However when one of the two is a different size the centered box is not truly centered anymore. Is there anyone that can help me?
Here's a method using flexbox to center the middle item, regardless of the width of siblings.
Key features:
pure CSS
no absolute positioning
no JS/jQuery
Use nested flex containers and auto margins:
.container {
display: flex;
}
.box {
flex: 1;
display: flex;
justify-content: center;
}
.box:first-child > span { margin-right: auto; }
.box:last-child > span { margin-left: auto; }
/* non-essential */
.box {
align-items: center;
border: 1px solid #ccc;
background-color: lightgreen;
height: 40px;
}
p {
text-align: center;
margin: 5px 0 0 0;
}
<div class="container">
<div class="box"><span>short text</span></div>
<div class="box"><span>centered text</span></div>
<div class="box"><span>loooooooooooooooong text</span></div>
</div>
<p>↑<br>true center</p>
Here's how it works:
The top-level div (.container) is a flex container.
Each child div (.box) is now a flex item.
Each .box item is given flex: 1 in order to distribute container space equally (more details).
Now the items are consuming all space in the row and are equal width.
Make each item a (nested) flex container and add justify-content: center.
Now each span element is a centered flex item.
Use flex auto margins to shift the outer spans left and right.
You could also forgo justify-content and use auto margins exclusively.
But justify-content can work here because auto margins always have priority.
8.1. Aligning with auto
margins
Prior to alignment via justify-content and align-self, any
positive free space is distributed to auto margins in that dimension.
Use three flex items in the container
Set flex: 1 to the first and last ones. This makes them grow equally to fill the available space left by the middle one.
Thus, the middle one will tend to be centered.
However, if the first or last item has a wide content, that flex item will also grow due to the new min-width: auto initial value.
Note Chrome doesn't seem to implement this properly. However, you can set min-width to -webkit-max-content or -webkit-min-content and it will work too.
Only in that case the middle element will be pushed out of the center.
.outer-wrapper {
display: flex;
}
.item {
background: lime;
margin: 5px;
}
.left.inner-wrapper, .right.inner-wrapper {
flex: 1;
display: flex;
min-width: -webkit-min-content; /* Workaround to Chrome bug */
}
.right.inner-wrapper {
justify-content: flex-end;
}
.animate {
animation: anim 5s infinite alternate;
}
#keyframes anim {
from { min-width: 0 }
to { min-width: 100vw; }
}
<div class="outer-wrapper">
<div class="left inner-wrapper">
<div class="item animate">Left</div>
</div>
<div class="center inner-wrapper">
<div class="item">Center</div>
</div>
<div class="right inner-wrapper">
<div class="item">Right</div>
</div>
</div>
<!-- Analogous to above --> <div class="outer-wrapper"><div class="left inner-wrapper"><div class="item">Left</div></div><div class="center inner-wrapper"><div class="item animate">Center</div></div><div class="right inner-wrapper"><div class="item">Right</div></div></div><div class="outer-wrapper"><div class="left inner-wrapper"><div class="item">Left</div></div><div class="center inner-wrapper"><div class="item">Center</div></div><div class="right inner-wrapper"><div class="item animate">Right</div></div></div>
The key is to use flex-basis. Then the solution is simple as:
.parent {
display: flex;
justify-content: space-between;
}
.left, .right {
flex-grow: 1;
flex-basis: 0;
}
CodePen is available here.
Here's an answer that uses grid instead of flexbox. This solution doesn't require extra grandchild elements in the HTML like the accepted answer does. And it works correctly even when the content on one side gets long enough to overflow into the center, unlike the grid answer from 2019.
The one thing this solution doesn't do is show an ellipsis or hide the extra content in the center box, as described in the question.
section {
display: grid;
grid-template-columns: 1fr auto 1fr;
}
section > *:last-child {
white-space: nowrap;
text-align: right;
}
/* not essential; just for demo purposes */
section {
background-color: #eee;
font-family: helvetica, arial;
font-size: 10pt;
padding: 4px;
}
section > * {
border: 1px solid #bbb;
padding: 2px;
}
<section>
<div>left</div>
<div>center</div>
<div>right side is longer</div>
</section>
<section>
<div>left</div>
<div>center</div>
<div>right side is much, much longer</div>
</section>
<section>
<div>left</div>
<div>center</div>
<div>right side is much, much longer, super long in fact</div>
</section>
Instead of defaulting to using flexbox, using grid solves it in 2 lines of CSS without additional markup inside the top level children.
HTML:
<header class="header">
<div class="left">variable content</div>
<div class="middle">variable content</div>
<div class="right">variable content which happens to be very long</div>
</header>
CSS:
.header {
display: grid;
grid-template-columns: [first] 20% auto [last] 20%;
}
.middle {
/* use either */
margin: 0 auto;
/* or */
text-align: center;
}
Flexbox rocks but shouldn't be the answer for everything. In this case grid is clearly the cleanest option.
Even made a codepen for your testing pleasure:
https://codepen.io/anon/pen/mooQOV
You can do this like so:
.bar {
display: flex;
background: #B0BEC5;
}
.l {
width: 50%;
flex-shrink: 1;
display: flex;
}
.l-content {
background: #9C27B0;
}
.m {
flex-shrink: 0;
}
.m-content {
text-align: center;
background: #2196F3;
}
.r {
width: 50%;
flex-shrink: 1;
display: flex;
flex-direction: row-reverse;
}
.r-content {
background: #E91E63;
}
<div class="bar">
<div class="l">
<div class="l-content">This is really long content. More content. So much content.</div>
</div>
<div class="m">
<div class="m-content">This will always be in the center.</div>
</div>
<div class="r">
<div class="r-content">This is short.</div>
</div>
</div>
Here is another way to do it, using display: flex in the parents and childs:
.Layout{
display: flex;
justify-content: center;
}
.Left{
display: flex;
justify-content: flex-start;
width: 100%;
}
.Right{
display: flex;
justify-content: flex-end;
width: 100%;
}
<div class = 'Layout'>
<div class = 'Left'>I'm on the left</div>
<div class = 'Mid'>Centered</div>
<div class = 'Right'>I'm on the right</div>
</div>
A slightly more robust grid solution looks like this:
.container {
overflow: hidden;
border-radius: 2px;
padding: 4px;
background: orange;
display: grid;
grid-template-columns: minmax(max-content, 1fr) auto minmax(max-content, 1fr);
}
.item > div {
display: inline-block;
padding: 6px;
border-radius: 2px;
background: teal;
}
.item:last-child > div {
float: right;
}
<div class="container">
<div class="item"><div contenteditable>edit the text to test the layout</div></div>
<div class="item"><div contenteditable>just click me and</div></div>
<div class="item"><div contenteditable>edit</div></div>
</div>
And here you can see it in Codepen: https://codepen.io/benshope2234/pen/qBmZJWN
I wanted the exact result shown in the question, I combined answers from gamliela and Erik Martín Jordán and it works best for me.
.parent {
display: flex;
justify-content: space-between;
}
.left, .right {
flex-grow: 1;
flex-basis: 0;
}
.right {
display: flex;
justify-content: flex-end;
}
you can also use this simple way to reach exact center alignment for middle element :
.container {
display: flex;
justify-content: space-between;
}
.container .sibling {
display: flex;
align-items: center;
height: 50px;
background-color: gray;
}
.container .sibling:first-child {
width: 50%;
display: flex;
justify-content: space-between;
}
.container .sibling:last-child {
justify-content: flex-end;
width: 50%;
box-sizing: border-box;
padding-left: 100px; /* .center's width divided by 2 */
}
.container .sibling:last-child .content {
text-align: right;
}
.container .sibling .center {
height: 100%;
width: 200px;
background-color: lightgreen;
transform: translateX(50%);
}
codepen: https://codepen.io/ErAz7/pen/mdeBKLG
Althought I might be late on this one, all those solutions seems complicated and may not work depending on the cases you're facing.
Very simply, just wrap the component you want to center with position : absolute, while letting the other two with justify-content : space-between, like so :
CSS:
.container {
display: flex;
justify-content: space-between;
align-items: center;
background-color: lightgray;
}
.middle {
position: absolute;
margin-left: auto;
margin-right: auto;
/* You should adapt percentages here if you have a background ; else, left: 0 and right: 0 should do the trick */
left: 40%;
right: 40%;
text-align: center;
}
/* non-essential, copied from #Brian Morearty answer */
.element {
border: 1px solid #ccc;
background-color: lightgreen;
}
p {
margin: 5px;
padding: 5px;
}
<div class="container">
<p class="element">First block</p>
<p class="middle element">Middle block</p>
<p class="element">Third THICC blockkkkkkkkk</p>
</div>
Michael Benjamin has a decent answer but there is no reason it can't / shouldn't be simplified further:
.container {
display: flex;
}
.box {
flex: 1;
display: flex;
justify-content: center;
}
.box:first-child { justify-content: left; }
.box:last-child { justify-content: right; }
And html
<div class="container">
<div class="box">short text</div>
<div class="box">centered tex</div>
<div class="box">loooooooooooooooong text</div>
</div>
I have three flex items all with different height and different widths.
I want the second and third items to be in relation to the first.
My first item is a image, second a text, third another text
I want my second item to be at the center of the flex box and the third to be at the start of second item. I also want the second item to grow and cover the rem area.
How I want my alignment
This is what I am doing
.box {
display: flex;
justify-content: flex-start;
}
.flex-second-item {
align-self: center;
flex-grow: 1
}
You just need to use different flexboxes for them
body {
display: flex;
gap: 10px;
align-items: center;
}
.one {
width: 100px;
height: 100px;
background: red;
}
.right-side {
display: flex;
gap: 10px;
}
.two {
width: 75px;
height: 75px;
background: red;
}
.three {
width: 50px;
height: 50px;
background: red;
}
<body>
<div class="one"></div>
<div class="right-side">
<div class="two"></div>
<div class="three"></div>
</div>
</body>
Hope it helps.
Regards
You can wrap second and third item in a div, and you display flex them with align-items=flex-start.
So you may try :
.first-box-and-div-which-contains-second-and-third-boxes {
display: flex;
align-items: center;
}
.second-and-third-boxes {
display: flex;
align-items: flex-start;
}
Imagine the following layout, where the dots represent the space between the boxes:
[Left box]......[Center box]......[Right box]
When I remove the right box, I like the center box to still be in the center, like so:
[Left box]......[Center box].................
The same goes for if I would remove the left box.
................[Center box].................
Now when the content within the center box gets longer, it will take up as much available space as needed while remaining centered. The left and right box will never shrink and thus when where is no space left the overflow:hidden and text-overflow: ellipsis will come in effect to break the content;
[Left box][Center boxxxxxxxxxxxxx][Right box]
All the above is my ideal situation, but I have no idea how to accomplish this effect. Because when I create a flex structure like so:
.parent {
display : flex; // flex box
justify-content : space-between; // horizontal alignment
align-content : center; // vertical alignment
}
If the left and right box would be exactly the same size, I get the desired effect. However when one of the two is from a different size the centered box is not truly centered anymore.
Is there anyone that can help me?
Update
A justify-self would be nice, this would be ideal:
.leftBox {
justify-self : flex-start;
}
.rightBox {
justify-self : flex-end;
}
If the left and right boxes would be exactly the same size, I get the desired effect. However when one of the two is a different size the centered box is not truly centered anymore. Is there anyone that can help me?
Here's a method using flexbox to center the middle item, regardless of the width of siblings.
Key features:
pure CSS
no absolute positioning
no JS/jQuery
Use nested flex containers and auto margins:
.container {
display: flex;
}
.box {
flex: 1;
display: flex;
justify-content: center;
}
.box:first-child > span { margin-right: auto; }
.box:last-child > span { margin-left: auto; }
/* non-essential */
.box {
align-items: center;
border: 1px solid #ccc;
background-color: lightgreen;
height: 40px;
}
p {
text-align: center;
margin: 5px 0 0 0;
}
<div class="container">
<div class="box"><span>short text</span></div>
<div class="box"><span>centered text</span></div>
<div class="box"><span>loooooooooooooooong text</span></div>
</div>
<p>↑<br>true center</p>
Here's how it works:
The top-level div (.container) is a flex container.
Each child div (.box) is now a flex item.
Each .box item is given flex: 1 in order to distribute container space equally (more details).
Now the items are consuming all space in the row and are equal width.
Make each item a (nested) flex container and add justify-content: center.
Now each span element is a centered flex item.
Use flex auto margins to shift the outer spans left and right.
You could also forgo justify-content and use auto margins exclusively.
But justify-content can work here because auto margins always have priority.
8.1. Aligning with auto
margins
Prior to alignment via justify-content and align-self, any
positive free space is distributed to auto margins in that dimension.
Use three flex items in the container
Set flex: 1 to the first and last ones. This makes them grow equally to fill the available space left by the middle one.
Thus, the middle one will tend to be centered.
However, if the first or last item has a wide content, that flex item will also grow due to the new min-width: auto initial value.
Note Chrome doesn't seem to implement this properly. However, you can set min-width to -webkit-max-content or -webkit-min-content and it will work too.
Only in that case the middle element will be pushed out of the center.
.outer-wrapper {
display: flex;
}
.item {
background: lime;
margin: 5px;
}
.left.inner-wrapper, .right.inner-wrapper {
flex: 1;
display: flex;
min-width: -webkit-min-content; /* Workaround to Chrome bug */
}
.right.inner-wrapper {
justify-content: flex-end;
}
.animate {
animation: anim 5s infinite alternate;
}
#keyframes anim {
from { min-width: 0 }
to { min-width: 100vw; }
}
<div class="outer-wrapper">
<div class="left inner-wrapper">
<div class="item animate">Left</div>
</div>
<div class="center inner-wrapper">
<div class="item">Center</div>
</div>
<div class="right inner-wrapper">
<div class="item">Right</div>
</div>
</div>
<!-- Analogous to above --> <div class="outer-wrapper"><div class="left inner-wrapper"><div class="item">Left</div></div><div class="center inner-wrapper"><div class="item animate">Center</div></div><div class="right inner-wrapper"><div class="item">Right</div></div></div><div class="outer-wrapper"><div class="left inner-wrapper"><div class="item">Left</div></div><div class="center inner-wrapper"><div class="item">Center</div></div><div class="right inner-wrapper"><div class="item animate">Right</div></div></div>
The key is to use flex-basis. Then the solution is simple as:
.parent {
display: flex;
justify-content: space-between;
}
.left, .right {
flex-grow: 1;
flex-basis: 0;
}
CodePen is available here.
Here's an answer that uses grid instead of flexbox. This solution doesn't require extra grandchild elements in the HTML like the accepted answer does. And it works correctly even when the content on one side gets long enough to overflow into the center, unlike the grid answer from 2019.
The one thing this solution doesn't do is show an ellipsis or hide the extra content in the center box, as described in the question.
section {
display: grid;
grid-template-columns: 1fr auto 1fr;
}
section > *:last-child {
white-space: nowrap;
text-align: right;
}
/* not essential; just for demo purposes */
section {
background-color: #eee;
font-family: helvetica, arial;
font-size: 10pt;
padding: 4px;
}
section > * {
border: 1px solid #bbb;
padding: 2px;
}
<section>
<div>left</div>
<div>center</div>
<div>right side is longer</div>
</section>
<section>
<div>left</div>
<div>center</div>
<div>right side is much, much longer</div>
</section>
<section>
<div>left</div>
<div>center</div>
<div>right side is much, much longer, super long in fact</div>
</section>
Instead of defaulting to using flexbox, using grid solves it in 2 lines of CSS without additional markup inside the top level children.
HTML:
<header class="header">
<div class="left">variable content</div>
<div class="middle">variable content</div>
<div class="right">variable content which happens to be very long</div>
</header>
CSS:
.header {
display: grid;
grid-template-columns: [first] 20% auto [last] 20%;
}
.middle {
/* use either */
margin: 0 auto;
/* or */
text-align: center;
}
Flexbox rocks but shouldn't be the answer for everything. In this case grid is clearly the cleanest option.
Even made a codepen for your testing pleasure:
https://codepen.io/anon/pen/mooQOV
You can do this like so:
.bar {
display: flex;
background: #B0BEC5;
}
.l {
width: 50%;
flex-shrink: 1;
display: flex;
}
.l-content {
background: #9C27B0;
}
.m {
flex-shrink: 0;
}
.m-content {
text-align: center;
background: #2196F3;
}
.r {
width: 50%;
flex-shrink: 1;
display: flex;
flex-direction: row-reverse;
}
.r-content {
background: #E91E63;
}
<div class="bar">
<div class="l">
<div class="l-content">This is really long content. More content. So much content.</div>
</div>
<div class="m">
<div class="m-content">This will always be in the center.</div>
</div>
<div class="r">
<div class="r-content">This is short.</div>
</div>
</div>
Here is another way to do it, using display: flex in the parents and childs:
.Layout{
display: flex;
justify-content: center;
}
.Left{
display: flex;
justify-content: flex-start;
width: 100%;
}
.Right{
display: flex;
justify-content: flex-end;
width: 100%;
}
<div class = 'Layout'>
<div class = 'Left'>I'm on the left</div>
<div class = 'Mid'>Centered</div>
<div class = 'Right'>I'm on the right</div>
</div>
A slightly more robust grid solution looks like this:
.container {
overflow: hidden;
border-radius: 2px;
padding: 4px;
background: orange;
display: grid;
grid-template-columns: minmax(max-content, 1fr) auto minmax(max-content, 1fr);
}
.item > div {
display: inline-block;
padding: 6px;
border-radius: 2px;
background: teal;
}
.item:last-child > div {
float: right;
}
<div class="container">
<div class="item"><div contenteditable>edit the text to test the layout</div></div>
<div class="item"><div contenteditable>just click me and</div></div>
<div class="item"><div contenteditable>edit</div></div>
</div>
And here you can see it in Codepen: https://codepen.io/benshope2234/pen/qBmZJWN
I wanted the exact result shown in the question, I combined answers from gamliela and Erik Martín Jordán and it works best for me.
.parent {
display: flex;
justify-content: space-between;
}
.left, .right {
flex-grow: 1;
flex-basis: 0;
}
.right {
display: flex;
justify-content: flex-end;
}
you can also use this simple way to reach exact center alignment for middle element :
.container {
display: flex;
justify-content: space-between;
}
.container .sibling {
display: flex;
align-items: center;
height: 50px;
background-color: gray;
}
.container .sibling:first-child {
width: 50%;
display: flex;
justify-content: space-between;
}
.container .sibling:last-child {
justify-content: flex-end;
width: 50%;
box-sizing: border-box;
padding-left: 100px; /* .center's width divided by 2 */
}
.container .sibling:last-child .content {
text-align: right;
}
.container .sibling .center {
height: 100%;
width: 200px;
background-color: lightgreen;
transform: translateX(50%);
}
codepen: https://codepen.io/ErAz7/pen/mdeBKLG
Althought I might be late on this one, all those solutions seems complicated and may not work depending on the cases you're facing.
Very simply, just wrap the component you want to center with position : absolute, while letting the other two with justify-content : space-between, like so :
CSS:
.container {
display: flex;
justify-content: space-between;
align-items: center;
background-color: lightgray;
}
.middle {
position: absolute;
margin-left: auto;
margin-right: auto;
/* You should adapt percentages here if you have a background ; else, left: 0 and right: 0 should do the trick */
left: 40%;
right: 40%;
text-align: center;
}
/* non-essential, copied from #Brian Morearty answer */
.element {
border: 1px solid #ccc;
background-color: lightgreen;
}
p {
margin: 5px;
padding: 5px;
}
<div class="container">
<p class="element">First block</p>
<p class="middle element">Middle block</p>
<p class="element">Third THICC blockkkkkkkkk</p>
</div>
Michael Benjamin has a decent answer but there is no reason it can't / shouldn't be simplified further:
.container {
display: flex;
}
.box {
flex: 1;
display: flex;
justify-content: center;
}
.box:first-child { justify-content: left; }
.box:last-child { justify-content: right; }
And html
<div class="container">
<div class="box">short text</div>
<div class="box">centered tex</div>
<div class="box">loooooooooooooooong text</div>
</div>
Well, here on this fiddle I have two divs aligned with display:flex and flex-grow: https://jsfiddle.net/h7bm23ts/2/
window.longer = function() {
document.getElementsByClassName("child2")[0].innerHTML += "like this and ";
};
* {
font-family: sans-serif;
}
.wrapper {
display: flex;
flex-direction: row;
flex-wrap: wrap;
}
.box1 {
background-color: beige;
height: 300px;
flex-grow: 2;
}
.box2 {
background-color: cyan;
height: 300px;
flex-grow: 1;
}
.child1 {
background-color: green;
}
.child2 {
background-color: gray;
}
<div class="wrapper">
<div class="box1">
some nonsense
</div>
<div class="box2">
longer nonsense <button onclick="window.longer();"> even longer </button>
<div class="child1">
this child should be able to expand this div
</div>
<div class="child2">
this child should wrap when too much content is appended
</div>
</div>
</div>
However, the content in one of the divs is dynamic and when more content is appended onto a child div of it, the parent div expands and makes the boxes wrap, ruining the layout with a few button clicks.
How do I keep the gray div from expanding on more content and make it simply accept its parent's width as "strict" and wrap in it?
EDIT: I settled on https://jsfiddle.net/h7bm23ts/12/.
Try this css to achive what you need:
.wrapper {
display: flex;
flex-direction: row;
flex-wrap: nowrap;
}
.box1 {
background-color: beige;
min-height: 300px;
flex: 2 1 0; /* 2 - flex grow, 1 - flex shrink, 0 - flex basis */
}
.box2 {
background-color: cyan;
min-height: 300px;
flex: 1 0 0;
}
More about this You can find here:
https://css-tricks.com/flex-grow-is-weird/ and here: https://drafts.csswg.org/css-flexbox/#flex-grow-property, and
https://drafts.csswg.org/css-flexbox/#flexibility
I have a web page using a column flexbox, with fixed size header and footer, and a content area which takes up the remaining space. This works fine.
The content area is a row flexbox, and I have 2 square divs side by side. I am making them square by using padding-bottom. This works fine, unless the window is >2x the content area height. Then my squares start bleeding into the footer, because padding is based on element width.
I would like the squares to never overlap the footer. I'm ok with there just being dead space to the right of the squares. I would like to stick with flexbox and avoid floats if possible. Only modern browsers need be supported.
Is this possible with only CSS? Or is this a job for JS.
Fiddle
html, body {
height: 100%;
margin: 0;
padding: 0;
}
#box {
display: flex;
flex-flow: column;
height: 100%;
}
div {
border: 1px solid tomato;
box-sizing: border-box;
margin: 0;
padding: 2px;
}
#header {
flex: 0 0 5em;
}
#footer {
flex: 0 0 5em;
}
#content {
background: blue;
display: flex;
flex: 1 1 auto;
flex-flow: row wrap;
min-height: 30%;
}
#content > div {
background: tomato;
border-color: black;
flex: 1 0 auto;
max-height: 50%;
padding-bottom: 50%;
}
<div id="box">
<div id="header">
<p><b>header</b>
</p>
</div>
<div id="content">
<div id='am'></div>
<div id='pm'></div>
</div>
<div id="footer">
<p><b>footer</b>
</p>
</div>
</div>
TIA!
Simple soluton:
#box
{
display: flex;
flex-flow: column;
min-height: 100%; /* this*/
}
JSfiddle Demo
Note: This assumes you want the page to overflow...but I didn't see any reference to containing the page height to the viewport.