Relative parent DIV to inherit the width of absolute child DIV - css

Question

I am trying to position a child DIV at the bottom of a parent DIV, but I would also like the contents of the child DIV to help dictate the dimensions of the parent DIV. As I have it right now, the child DIV doesn't affect the width/height of the parent DIV.
Here is a sample of my HTML/CSS code:
//HTML code:
<div id="parent">
<h3>Top Aligned Title</h3>
<div id="child"></div>
</div>
//CSS code:
#parent {
background-color:#222;
position: relative;
height: 500px;
}
#child {
background-color:#444;
position: absolute;
bottom: 0px;
width: 100px;
height: 200px;
}
What do I need to do it achieve what I am trying to do? I could forgo the absolute/relative CSS rules and simply create a table within the parent DIV which would allow me to achieve both bottom alignment and content that dictates the parent's dimensions.
However, I'd like to know if there a way to do this in CSS and without having to set the width of the parent DIV.
thanks in advance!

Answer 1

The short answer is that what you are asking basically can't be done with pure CSS / HTML. (at least without tables) You'd need Javascript that would read #child's width/height and then do the calculation you want to do (I don't know) and set a new height/width to #parent.
Otherwise, if you mean that you want #child's height/width to change according to its content, of course this is native CSS, just set it's height/width to auto and then start adding text inside it you'll see it will start growing to fit your content inside.
As the #child is positioned absolute, then it is taken OUT of the normal flow of the document, therefore it will not affect the #parent.

Answer 2

With modern CSS, this is doable.
HTML:
<div id="parent">
<h3>Top Aligned Title</h3>
<div id="child">
<p>CHILD ELEMENT</p>
</div>
</div>
CSS:
#parent {
background:red;
height: 500px;
position:relative;
}
#child {
background:green;
position: absolute;
top:100%;
-webkit-transform: translateY(-100%);
-ms-transform: translateY(-100%);
transform: translateY(-100%);
width: 100px;
}
http://jsfiddle.net/Bushwazi/bpe5s6x3/
transform:translateY(-100%); is the trick. It's math is based on the element's box-model.
You could also combine top:50%; with transform:translateY(-50%); to center it.
You can swap top for left and translateY for translateX to position the element horizontally.

Answer 3

Here you go
HTML:
<main id="parent">
<div class="popup">Top Aligned Title
<div class="content">
Content
</div>
</div>
</main>
CSS:
#parent {
width: 120px;
}
.popup {
position: relative;
margin-top: 48px;
}
.content {
left: 0;
position: absolute;
background: green;
width: 100%;
}
http://jsfiddle.net/8L9votay/

Answer 4

You can play around with flex and zero-width/height.
I've recently come up with the following solution (for width):
#parent {
display: inline-flex;
flex-direction: column;
background: #518cff;
color: #fff;
}
#child-wrapper {
height: 0; /* This can also be max-height, but height is just enough */
}
#child {
transform: translateY(-100%); /* If you need to align child to the bottom */
background: #b40000;
color: #fff;
}
<div id="parent">
<h3>Top Aligned Title</h3>
<div id="child-wrapper"> <!-- This is the solution -->
<div id="child">
Child's content that is longer than parent's
</div>
</div>
</div>