CSS: fixed-width sidebar with fluid-width content container.

home.html

<div id="content-wrapper">
    <div id="content">
        <!-- blah blah blah -->
    </div>
</div>

<div id="sidebar">
    <ul>
        <!-- blah blah blah -->
    </ul>
</div>

style.css

#sidebar {
    width: 200px; /* sidebar width */
    float: left;
    margin-left: -100%;
}

#content {
    margin-left: 200px; /* sidebar width */
}

#content-wrapper {
    width: 100%;
    float: left;
}