CSS and responsiveness in multiple columns with fixed and scaleable elements can be done in many ways.
I have created a solution that seems to work, though I have no idea whether this is best practice.
CSS
html, body { margin:0 auto; padding:0; background: #fff; text-align: center; }
/* Clearfix
============================================================================ */
.CF { display:inline-block;overflow:hidden; }
/* IE mac \*/
.CF { display:block; }
/* Elements
============================================================================ */
div#container {max-width: 1140px; min-width: 960px; margin:0 auto; margin-top: 10px; padding:0; background:#0F9; position:relative;}
div#left-menu {width: 100px; background:#F30; position: absolute; top:0; left:0; }
div#information {padding: 10px 10px 25px 10px; background:#39C; margin-left:100px;}
div#information-wrapper {position:relative; background:#3FF; }
div#information-left-menu {width: 125px; background:#C30; position: absolute; top: 0; left:0;}
div#content {background:#FC0; margin-left: 125px; text-align:left;}
HTML
<div id="container" class="CF" >
<!-- This is fixed Width -->
<div id="left-menu">
<p>Left 100px wide </p>
</div>
<!-- Width scales to size of Container -->
<div id="information" class="CF">
<div id="information-wrapper">
<div id="information-left-menu">Fixed width of 125px </div>
<div id="content">text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text </div>
</div>
</div>
</div><!-- / END / Container / -->
