fixed fluid layout

  <div id="fixed">Sidebar</div>
  <div id="fluid">Content</div>

#fixed, #fluid{
    padding:20px;
    margin-left:2px;
    margin-right:2px;
}
#fixed {
    float:left;
    width:150px;
    background-color:#ccc;
}
#fluid {
    overflow:hidden;/*没有此属性的话margin会失效*/
    background-color:#999999;
}

http://jsfiddle.net/hhcncku5/