Question

How do I keep a resizable div from being overlapped by neighboring elements? I changed the z-index of the resizable div to have 1, and the rest 0.

This example will make it clear right away:
http://jsfiddle.net/gALUP/1/

HTML

<div id='grid'>
    <div class='outline'>
        <div class='container resizable'>
        </div>    
    </div>
    <div class='outline'>
        <div class='container'>
        </div>    
    </div>
</div>

CSS

.outline { 
    height: 200px;
    width: 200px;
    border: 1px solid black; 
    position: relative; 
    z-index: 0; 
    display: inline-block;
}
.container { 
    height: 100%; 
    width: 100%; 
    background-color: #ff0000;
}

.resizable { 
    background-color: #0000ff; 
    position: absolute; 
    z-index: 1; 
}

Answer 1

Remove z-index: 0 from .outline:

.outline {
    height: 200px;
    width: 200px;
    border: 1px solid black;
    position: relative;
    display: inline-block;
}
.container {
    height: 100%;
    width: 100%;
    background-color: #ff0000;
}
.resizable {
    background-color: #0000ff;
    position: absolute;
    z-index: 1;
}

http://jsfiddle.net/elclanrs/gALUP/2/