Smells Like Bakin Grids and CSS don't work

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  <ul class="nav">
    <li><a href="#">About</a></li>
    <li><a href="#">Cupcakes &amp; Prices</a></li>
    <li><a href="#">Locations</a></li>
    <li class="lastalt"><a href="#">Contact Us</a></li>
  </ul>
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<div id="intro" class="grid_9">
  <h1>Opposites really do attract, especially in our kitchen! We combine unexpected flavors that melt together to create ironically delicious desserts.</h1>
  <p><a href="#" class="btn">Browse Our Cupcakes</a></p>
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  <img src="img/you-bake-me-blush.gif" alt="You Bake Me Blush">
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<div id="feautured-cupcake" class="grid_7">
  <h2>Cupcake of the Week</h2>
  <p>This week's featured cupcake is the <a href="#">Avacado Chocolate Cupcake</a>. Its strange combo of flavors will kick your taste buds into fiesta mode!</p>
  <img src="img/featured-cupcake.jpg" alt="Avocado Chocolate Cupcake">
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<div id="new-cupcakes" class="grid_5 omega">
  <h2>Fresh Out of the Oven</h2>
  <p>Our newest cupcakes are <a href="#">Bacon Me Crazy</a> and <a href="#">Jalapeno So Spicy</a>. </p>
  <img src="img/new-cupcake-bacon.jpg" alt="Bacon Me Crazy">
  <img src="img/new-cupcake-jalapeno.jpg" alt="Jalapeno So Spicy">
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<div class="grid_7">
  <h2>Inside the Kitchen</h2>
  <p>Smells Like Bakin' started out in the garage of the husband wife duo Allison &amp; Joseph. Allison is the baker, and Joseph found a way for them to make a business out of her tasty treats. Flash forward to today and they have a successful store front, catering business and cupcake truck. </p>
  <p><a href="#" class"btn-small">Read More</a></p>
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  <h2>Get Bakin' with Us</h2>

  <div id="contact">
    <p>Call Us: <span>1-555-CUP-CAKE</span><br>
      Email Us: <a href="#">bakeon@smellslikebakin.com</a></p>
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<p>We announce all of our new flavours first through Facebook &amp; Twitter, and even take requests!</p>
<a href="http://www.facebook.com/SmellsLikeBakin"><img src="img/facebook.gif" alt="Facebook"></a>
<a href="https://twitter.com/#!/smellslikebakin"><img src="img/twitter.gif" alt="Twitter"></a>

<div id="copyright">
  <p>&copy; 2013 Smells like Bakin' Cupcake Company. All Rights Reserved.</p>.
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