atom/HTML/tabs.html

<style>
  * { margin: 0; padding: 0; }
  body {
      font: 12px "Lucida Grande", Helvetica, Arial, serif;
      overflow: hidden;
  }
  iframe { border: 0; }

  .clearfix:after {
      visibility: hidden;
      display: block;
      font-size: 0;
      content: " ";
      clear: both;
      height: 0;
  }

  #tabs {
      background: -webkit-gradient(linear, left top, left bottom, from(#EEEEEE), to(#D8D7D8));
      padding: 3px 0 0 0;
  }

  #tabs .add a {
      width: 12px;
      height: 12px;

      margin-top: 2px;
      margin-left: 10px;
      padding: 2px;

      font-size: 15px;
      font-weight: bold;
      color: #fff;
      text-shadow: #000 1px 1px 0;
      background: #d8d7d8;
      border: 1px solid #a0a0a0;
      border-bottom: none;

      -webkit-border-top-right-radius: 10px 5px;
      -webkit-border-top-left-radius: 10px 5px;
      -webkit-box-shadow: inset 0 1px 0 white;
  }
  #tabs .add span {
      display: block;
      margin-top: -4px;
  }

  #tabs ul {
      list-style: none;
      border-bottom: 1px solid #a0a0a0;
  }
  #tabs ul li { display: inline; }

  #tabs ul li.active a {
      position: relative;
      z-index: 1;
      height: 8px;

      background: #eee;
      padding-top: 4px;
  }

  #tabs ul li a {
      display: block;
      float: left;
      text-decoration: none;
      position: relative;
      height: 8px;

      padding: 3px 50px 7px;
      margin: 0 -5px 0 0;
      color: #222;
      background: #d8d7d8;

      -webkit-border-top-right-radius: 10px 20px;
      -webkit-border-top-left-radius: 10px 20px;
      -webkit-box-shadow: inset 1px 1px 0 white;

      border: 1px solid #a0a0a0;
      border-bottom: 0;
  }

  .content {
      -webkit-box-shadow: inset 0 1px 0 white;
      -moz-box-shadow: inset 0 1px 0 white;
      height: 97%;
  }
</style>

<div id="tabs">
  <ul class="clearfix">
    <li class="active"><a href="#">untitled</a></li>
    <li class="add"><a href="#"><span>+</span></a></li>
  </ul>
</div>

<div class="content">
  <%= editor %>
</div>