Left, center, and right align divs on bottom of same line

To make your center div elastic, you could do something like:

<div style="display:table; width:500px;">
  <div style="display:table-row;">
    <div style="display:table-cell; width:50px;"></div>
    <div style="display:table-cell;"></div>
    <div style="display:table-cell; width:50px;"></div>
  </div>
</div>

My technique is similar to @Damien-at-SF:

I tried to rigorously demonstrate all the requirements you asked for.

Live Demo

HTML:

<div id="container">

    <div id="left"></div>
    <div id="mid"></div>
    <div id="right"></div>

</div>

CSS:

#container {
    position: relative;
    height: 400px;
    width: 80%;
    min-width: 400px;
    margin: 0 auto;

    background: #ccc
}
#left, #right, #mid {
    position: absolute;
    bottom: 0;
}
#left {
    left: 0;
    width: 80px;
    height: 200px;

    background: red
}
#right {
    right: 0;
    width: 120px;
    height: 170px;

    background: blue
}

#mid {
    left:50%;

    margin-left: -80px;
    width: 160px;
    height: 300px;

    background: #f39
}

A further enhancement to the first answer:

In the "center" div CSS, you need to add:

text-align:center;

In the "right" div CSS, you need to add:

text-align:right;

... to perfectly achieve left/center/right aligning.

By setting your container div to position:relative and the child divs to position:absolute you can absolute position the divs within the confines of the container.

This makes it easy, as you can use bottom:0px to align all vertically to the bottom of the container, and then use left/right styling to position along the horizontal axis.

I set up a working jsFiddle: http://jsfiddle.net/Damien_at_SF/KM7sQ/5/ and the code follows:

HTML:

<div id="container">
    <div id="left">left</div>
    <div id="center">center</div>
    <div id="right">right</div>    
</div>

CSS:

#container {
    position:relative;
    height:400px;
    width:100%;
    border:thick solid black;
}
#container div {
    background:grey;
    width:200px;
}
#left {
    position:absolute;
    left:0px;
    bottom:0px;
}
#center {
    position:absolute;
    left:50%;
    margin-left:-100px;
    bottom:0px;
}
#right {
    position:absolute;
    right:0px;
    bottom:0px;
}

Note: For the "center" div, the margin-left = 1/2 the width of the div :)

Hope that helps :)