Middle floating div between two fixed divs

index.html

<div id="leftCol">Left</div>
<div id="rightCol">Right</div>
<div id="centerCol">Center</div>

style.css

#leftCol {float: left; width: 75px; background: red; min-height: 100px;}
#rightCol {float: right; width: 175px; background: green; min-height: 100px;}
#centerCol {overflow: hidden; background: blue; min-height: 100px;}