<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Simple grid</title>
    <style>

    * { box-sizing: border-box; }

    body {
      width: 980px;
      margin: 0 auto;
    }

    .wrapper {
      padding-right: 20px;
    }

    .row {
      clear: both;
    }

    .col {
      float: left;
      margin-left: 20px;
      width: 60px;
      background: rgb(255,150,150);
    }

    /* Two column widths (120px) plus one gutter width (20px) */
    .col.span2 { width: 140px; }
    /* Three column widths (180px) plus two gutter widths (40px) */
    .col.span3 { width: 220px; }
    /* And so on... */
    .col.span4 { width: 300px; }
    .col.span5 { width: 380px; }
    .col.span6 { width: 460px; }
    .col.span7 { width: 540px; }
    .col.span8 { width: 620px; }
    .col.span9 { width: 700px; }
    .col.span10 { width: 780px; }
    .col.span11 { width: 860px; }
    .col.span12 { width: 940px; }

    </style>
  </head>

  <body>
    <div class="wrapper">
      <div class="row">
        <div class="col">1</div>
        <div class="col">2</div>
        <div class="col">3</div>
        <div class="col">4</div>
        <div class="col">5</div>
        <div class="col">6</div>
        <div class="col">7</div>
        <div class="col">8</div>
        <div class="col">9</div>
        <div class="col">10</div>
        <div class="col">11</div>
        <div class="col">12</div>
      </div>
      <div class="row">
        <div class="col span1">13</div>
        <div class="col span6">14</div>
        <div class="col span3">15</div>
        <div class="col span2">16</div>
      </div>
    </div>
  </body>
</html>
