Update logo, adjust styles to match main website.

h/static/styles/app.scss

@@ -152,9 +152,9 @@ ol {
   .masthead-heading {
     margin: 0;
     padding-top: 4px;
-    font-size: 1.2em;
+    font-size: 1.1em;
     font-weight: 400;
-    color: $gray-light;
+    color: $gray;
 
     &:hover {
       color: $gray-dark;
@@ -174,7 +174,7 @@ ol {
   }
 
   .masthead-heading {
-    font-size: 20px;
+    font-size: 1.1em;
     line-height: 1em;
   }
 

h/static/styles/help-page.scss

@@ -33,7 +33,8 @@
 .help-page-heading {
   color: $gray-darker;
   margin-bottom: 1em;
-  font-size: 1.5em;
+  font-weight: 400;
+  font-size: 1.1em;
 }
 
 .help-page-lede {
@@ -131,7 +132,8 @@
 
 .feature-heading {
   color: $gray-darker;
-  font-size: 1.125em;
+  font-size: 1em;
+  font-weight: 400;
   margin-bottom: .555em;
 }