How about fixing the height of your div to be exactly two lines high, and using overflow:hidden;?
For example:
<style type="text/css">
  .twolines
  {
     font-size: 20px;
     height: 48px;
     overflow: hidden;
  }
</style>
You could also use em values and line-height:
<style type="text/css">
  .twolines
  {
     font-size: 1em;
     line-height: 1em;
     height: 2em;
     overflow: hidden;
  }
</style>
Here's a complete, working example:
<!DOCTYPE html>
<html>
<head>
  <style type="text/css">
     .twolines
     {
        font-size: 1em;
        background-color: silver;
        line-height: 1em;
        height: 2em;
        overflow: hidden;
     }
     .twolines p
     {
        margin: 0;
     }
  </style>
</head>
<body>
  <div class="twolines">
     <p>Long text continues</p>
     <p>down the road</p>
     <p>into a lane.</p>
  </div>
</body>
</html>