Update headings for semantasticality (Bug 730809)

apps/b2g/templates/b2g/b2g.html

@@ -21,10 +21,10 @@
 
 <h1 id="main-feature">Bringing the Open Web to <span class="large">Mobile Devices</span></h1>
 
-<section id="primary" class="container">
+<section id="primary" class="billboard">
 
   <img src="{{ MEDIA_URL }}img/b2g/hero.png" alt="" />
-  <h1>Welcome to a new, open and powerful mobile world!</h1>
+  <h2>Welcome to a new, open and powerful mobile world!</h2>
   <p>We launched the Boot to Gecko project to enable the Open Web as a platform for mobile devices. We’re making innovation possible by driving the development of new Web standards.</p>
 
 </section>

media/css/b2g.less

@@ -5,13 +5,7 @@ h1#main-feature {
 }
 
 #primary {
-    padding-top: @baseLine * 2;
-    padding-bottom: @baseLine * 2;
-    @shadow: 0 1px 1px rgba(0,0,0,0.1), 0 0 0 1px #fff;
-    .box-shadow(@shadow);
-    background: #fff;
     #gradient > .radial(center, 45px, ellipse, farthest-corner, #f5f1e8 0%, #ffffff 100%);
-    .clearfix;
     height: 13em;
     margin-bottom: @baseLine * 3;
 

media/css/sandstone/sandstone.less

@@ -58,7 +58,8 @@ h1, h2, h3, h4, h5, h6, .huge, .large {
 }
 
 h1,
-.large h2 {
+.large h2,
+.billboard h2 {
     font-size: 48px;
     letter-spacing: -2px;
 }
@@ -531,7 +532,8 @@ px      68    160    252    */
         letter-spacing: -1px;
     }
 
-    h2 {
+    h2,
+    .billboard h2 {
         font-size: 28px;
         letter-spacing: -0.5px;
     }