简单 3 个固定宽度列布局

HTML：

<div class="wrapper">
  <div class="left-sidebar">
    <h1>Left Sidebar</h1>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. </p>
  </div>
  <div class="content">
    <h1>Content</h1>
    <p>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim lacinia nunc. Curabitur tortor. Pellentesque nibh. Aenean quam. In scelerisque sem at dolor. Maecenas mattis. Sed convallis tristique sem. Proin ut ligula vel nunc egestas porttitor. Morbi lectus risus, iaculis vel, suscipit quis, luctus non, massa. </p>
  </div>
  <div class="right-sidebar">
    <h1>Right Sidebar</h1>
    <p>Fusce ac turpis quis ligula lacinia aliquet.</p>
  </div>
</div>

CSS：

.wrapper {
  width:600px;
  background-color:pink;
  padding:20px;

  /* Floated elements don't use any height. Adding "overflow:hidden;" forces the
     parent element to expand to contain its floated children. */
  overflow:hidden;
}

.left-sidebar {
  width:150px;
  background-color:blue;
  float:left;
}

.content {
  width:300px;
  background-color:yellow;
  float:left;
}

.right-sidebar {
  width:150px;
  background-color:green;
  float:right;
}