Fix HTML on letters page

app/templates/views/features/letters.html

@@ -13,12 +13,12 @@
     {{ sub_navigation(navigation_links) }}
   </div>
   <div class="column-two-thirds">
-    
+
     <h1 class="heading heading-large">Letters</h1>
     <p>GOV.UK Notify will print, pack and post your letters for you.</p>
     <p><a href="https://www.notifications.service.gov.uk/register">Create an account</a> and try Notify for yourself.</p>
-    
-    <h2 class="heading heading-medium">Features</p>
+
+    <h2 class="heading heading-medium">Features</h2>
     <p>Notify makes it easy to:</p>
     <ul class="list list-bullet">
       <li>create reusable letter templates</li>
@@ -27,15 +27,15 @@
     </ul>
     <p>You can also <a href="https://www.notifications.service.gov.uk/documentation">integrate with our API</a> to send letters automatically.</p>
 
-    <h3>Choose your postage</h3>
+    <h3 class="heading-small">Choose your postage</h3>
     <p>You can send letters by first or second class postage.</p>
     <p>First class letters are delivered one day after they're dispatched. Second class letters are delivered 2 days after they're dispatched.</p>
     <p>Letters sent before 5:30pm are dispatched the next working day (Monday to Friday). Royal Mail delivers from Monday to Saturday, excluding bank holidays.</p>
-    
+
     <h3 class="heading heading-small">Upload your own letters</h3>
     <p>You can create reusable letter templates in Notify, or upload and send your own letters.</p>
     <p>Use the <a href="https://docs.notifications.service.gov.uk/documentation/images/notify-pdf-letter-spec-v2.3.pdf">letter specification document</a> to help you set up your letter, save it as a PDF, then upload it to Notify.<p>
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+
     <h2 class="heading heading-medium">Pricing</h2>
     <p>It costs between 30p and 76p to send a letter. Prices include:</p>
     <ul class="list list-bullet">
@@ -49,5 +49,5 @@
 
   </div>
 </div>
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+
 {% endblock %}