Flexbox many nested children - html

Question

I've read many posts on flexbox but still have an issue that bugs me.
I want to have a sticky footer using flexbox as per this guide.
But then, inside my page content I would like to have as many nested divs I like and have them taking the same height of the parent.
The problem is, setting height: 100% on each child (as I would do in a non-flexbox scenario) works differently when flexbox is enabled. This results in the children getting more height (overflow the parent).
To make this more clear here's a codepen without flexbox
and a codepen with flexbox
You can see in the flexbox scenario the footer gets the green bakground even if I don't want that.
HTML:
<div class="sticky-footer-container">
<div class="sticky-footer-content">
<div class="page-container">
<div class="main-menu">
<div class="main-menu-selection">
<div class="main-menu-selection-text">
<div class="some-other-class">
Some text
</div>
</div>
</div>
<div class="main-menu-selection">
<div class="main-menu-selection-text">
<div class="some-other-class">
Some text
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sticky-footer">
Some footer content
</div>
</div>
SCSS:
* {
box-sizing: border-box;
}
html,
body {
height: 100%;
background: silver;
padding: 0;
margin: 0;
}
.sticky-footer-container {
height: 100%;
display: flex;
flex-direction: column;
.sticky-footer-content {
height: 100%;
background: blue;
flex: 1;
div {
height: 100%;
}
.main-menu-selection {
height: 50%;
}
}
}
.some-other-class {
background: green;
}
In order to solve this, ANY nested div has to become a flex-container ?
In other words, is there any way to "stop the flex propagation" at some point of the tree, so all the divs gets the parent height without overflow?

Answer 1

display:flexbox is not really a valid value :)
you need to set height as well and eventually inherit it from html :
.sticky-footer-container {
display: flex;
flex-direction: column;
}
.sticky-footer-content {
flex: 1;
}
/* let's inherit some height to pull the footer down */
html,
body,
.sticky-footer-container {
height: 100%;
margin: 0;
}
.sticky-footer {
display: flex;/* flex item can be flexboxes as well */
background: turquoise;
align-items: center;
justify-content: center;
min-height: 3em;
}
<div class="sticky-footer-container">
<div class="sticky-footer-content">
<div class="page-container">
<div class="main-menu">
<div class="main-menu-selection">
<div class="main-menu-selection-text">
<div class="some-other-class">
Some text
</div>
</div>
</div>
<div class="main-menu-selection">
<div class="main-menu-selection-text">
<div class="some-other-class">
Some text
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sticky-footer">
Here my footer
</div>
</div>