这就是你需要的
http://jsfiddle.net/fxWg7/790/
HTML
<div class="container">
<div class="left">
content fixed width
</div>
<div class="right">
content flexible width
</div>
</div>
CSS
.container {
height: auto;
overflow: hidden;
}
.left {
width: 300px;
float: left;
background: #aafed6;
}
.right {
float: none; /* not needed, just for clarification */
background: #e8f6fe;
/* the next props are meant to keep this block independent from the other floated one */
min-width:300px;
width: auto;
max-width:500px; /* not neccessary */
overflow: hidden;
}