Div to take up entire remaining width [duplicate]

Answer 1

You could also work with an absolute position for the right side column. Consider this example:

.parent{
    width:100%;
    height:50px;
    background:#888;
    position:relative
}
.left{
    float:left;
    height:100%;
    width:50px;
    background:green
}
.right{
    background:red;
    position:absolute;
    bottom:0;
    left:50px;
    right:0;
    top:0
}

Also see this Fiddle. Note that you would need to set position: relative on the parent container for this to fly.