Relative parent DIV to inherit the width of absolute child DIV

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/

1. transform:translateY(-100%); is the trick. It's math is based on the element's box-model.
2. You could also combine top:50%; with transform:translateY(-50%); to center it.
3. You can swap top for left and translateY for translateX to position the element horizontally.