<div class="a"></div>
<div class="b"></div>
<div class="c"></div>
<div class="d"></div>
<div class="c"></div>
<div class="a"></div>
<div class="d"></div>
<div class="b"></div>

div{
  height: 50px;
  min-width: 50px;
}
div.a{
  background: #00FF00;
}
div.b{
  background: #1234FF;
}
div.c{
  background: #FbbF00;
}
div.d{
  background: #FF3344;
}

<div class="row-fluid">
  <div class="span 3">
    <div class="a"></div>
    <div class="b"></div>
  </div>
  <div class="span 3">
    <div class="c"></div>
    <div class="d"></div>
  </div>
  <div class="span 3">
    <div class="c"></div>
    <div class="a"></div>
  </div>
  <div class="span 3">
    <div class="d"></div>
    <div class="b"></div>
  </div>

div{
    height: 50px;
    min-width: 50px;
    display: inline-block;
  }
  div.a{
    background: #00FF00;
  }
  div.b{
    background: #1234FF;
  }
  div.c{
    background: #FbbF00;
  }
  div.d{
    background: #FF3344;
  }