How to Set Dynamic Width DIVs

Question

Here is my scenario. I have a container div that has (n) child elements inside it. For this instance lets say there are 2 divs within the container div:

<div id="container">
    <div id="col1">
        Stuff in col1
    </div>
    <div id="col2">
        Stuff in col2
    </div>
</div>

The container div is going to be a percentage of the viewport, say 80%. Now, what I'm looking for is for these two inner divs (col1 & col2) to be inline with each other and take up the same amount of space. So the result should look something like this:

+-------------- container -------------+
|  +---- col1 ----+  +---- col2 ----+  |
|  | stuff in     |  | stuff in     |  |
|  | col1         |  | col2         |  |
|  +--------------+  +--------------+  |
+--------------------------------------+

Or if the container width is changed should result in something like this:

+------------------------------ container -----------------------------+
|  +------------ col1 ------------+  +------------ col2 ------------+  |
|  | stuff in col1                |  | stuff in col2                |  |
|  | stuff in col1                |  | stuff in col2                |  |
|  +------------------------------+  +------------------------------+  |
+----------------------------------------------------------------------+

The inner divs are always of equal width and have some separation from each other. This is similar to a table layout, but I would rather not use tables if possible. I have tried various techniques like floating and displaying the divs inline to no avail. They can never seem to align just right.

Answer 1

make col1 and col2 spans (not divs) with

vertical-align:top
display:inline-block
width:50%

obviously (adjust the width to account for your margins/padding. and recommended that you use percentages for margins/padding so they add up to just under 100% see:http://ejohn.org/blog/sub-pixel-problems-in-css/)

Answer 2

Table cells could stretch automatically. It's not exactly possible with div, so you have to specify appropriate width for each column by hand. For example:

#col1, #col2 {
    float: left;
    width: 50%;
}

Answer 3

My preferred solution

Use positioning relative to the outer container:

#container, #container > div  
{
    position: relative;
}

#col1  
{
     left: 2%; /* your margin */
}

#col2  
{
     right: 2%;
}

#container > div 
{
     width: 47%;
}

Note that you leave approximately the same 2% in the middle. The #col1 and #col2 should be aligned now.

Other solutions

With CSS3: use column-count: 2 and break column after first div.

If you really feel like floating, do only #col1 { float: left; width: 50%; }

Answer 4

#container{
overflow: hidden
} 

#col1, #col2 {
    float: left;
    width: 50%;
}