Fix typo, revise 50/50 layout

Author: jordanmccullough

index.html

@@ -50,25 +50,30 @@ <h3>Advanced</h3>
 
 <section class="grey">
   <div class="container">
+    <div class="half">
+      <div class="workbook"></div>
+    </div>
     <div class="half">
       <div class="content">
-        <h3>Workbook for teaching narratives</h3>
+        <h2>Workbook for teaching narratives</h2>
         <p>
-          Teach or learn from GitHub's very own class curriclum narrative.<br>
+          Teach or learn from GitHub's very own class curriculum narrative.<br>
           From outline to full workflow, learn everything Git and GitHub.
         </p>
 
         <a href="workbooks/github-foundations.html">Foundations</a> |
         <a href="workbooks/github-intermediate.html">Intermediate</a> |
         <a href="workbooks/github-advanced.html">Advanced</a>
       </div>
-
-      <div class="workbook"></div>
     </div>
+  </div>
+</section>
 
+<section>
+  <div class="container">
     <div class="half">
       <div class="content">
-        <h3>Downloads to reference anytime</h3>
+        <h2>Downloads to reference anytime</h2>
         <p>
           Looking for a quick reference sheet of Git commands?<br>
           We've got you covered.
@@ -78,13 +83,15 @@ <h3>Downloads to reference anytime</h3>
           Download the PDF
         </a>
       </div>
+    </div>
 
+    <div class="half">
       <div class="downloads"></div>
     </div>
   </div>
 </section>
 
-<section>
+<section class="grey">
   <div class="container">
     <div class="half">
       <div class="content">
@@ -94,7 +101,7 @@ <h3>Community contributions</h3>
           Just fork the repository, make your changes, and submit a Pull Request.
         </p>
         <p>
-          <a href="https://github.com/github/training-kit">Head over to the github/training-kit repository.</a>
+          <a href="https://github.com/github/training-kit">Head over to the github/training-kit repository</a>
         </p>
       </div>
     </div>