prototype for Turbulence homepage

<!DOCTYPE html>
<meta charset="utf-8">
<style>
  body {
    margin: 0;
  }
  .container {
    width: 100%;
  }
  .container > header,
  .container > section {
    left: 50%;
    margin-left: -512px;
    width: 1024px;
  }
  .container > header,
  .container > section .grid {
    background: url(https://cdn.invisionapp.com/cdn/10c26a71aceec73b766c717532c66ca3/screens/53588992/2/mhdsKGgGUQA4I4AArdfUXGlGOqRg9m8XXu6cbNvbefdZJLinq4FX1ufqMr2j7RW4B3GfolJzH4L9PSg9qiwdtg4/Desktop.png) 0 0 no-repeat;
  }
  #scroll-down {
    display: block;
    width: 45px;
    height: 25px;
    z-index: 25;
    background: url(https://projects.invisionapp.com/assets/2403969/1097714/4AEA90F27E77C1C1F2C737BBF0DE44C8B5E7FB7AA5740011B3AD381F70C6DAF8/preview?w=758);
    top: 612px;
    left: 50%;
    margin-left: -22.5px;
    position: fixed;
  }
  header {
    z-index: 10;
    top: 0;
    overflow: hidden;
    position: fixed;
    color: white;
    height: 650px;
    z-index: 100;
  }
  #l2 {
    background-position: 0 -656px;
    z-index: 0;
    height: 450px;
  }
  #l2 h1 {
    color: red;
  }
  #l3 {
    position: absolute;
    z-index: 20;
    margin-top: 660px;
  }
  #l3 .gap {
    height: 450px;
  }
  #l3 .grid {
    width: 100%;
    height: 2000px;
    background-position: 0 -1122px;
    background-color: #fff;
  }
</style>

Modified http://code.jquery.com/jquery-2.1.1.min.js to a secure url

https://code.jquery.com/jquery-2.1.1.min.js