Edit in JSFiddle

<div id="wrapper">
  <div id="content">
    <div id="slider">slider</div>
    <div id="left">left</div>
    <div id="right">right</div>
    <div class="clear"></div>
    <!-- THIS -->
  </div>
</div>

#wrapper {
  background: blue;
  width: 390px;
  margin: 0 auto;
}

#content {
  width: 390px;
  height: auto;
}

#slider {
  width: 390px;
  /* slider jquery   */
  height: auto;
}

#left {
  float: left;
  width: 190px;
}

#right {
  float: right;
  width: 190px;
}