Move inline CSS on old homepage into its own CSS file

It lives in it's own CSS file (`styles/old-home.css`) to make it easier
to delete once we remove the old homepage.

gulpfile.js

@@ -162,6 +162,7 @@ var styleFiles = [
   './h/static/styles/front-page/main.css',
   './h/static/styles/help-page.scss',
   './h/static/styles/site.scss',
+  './h/static/styles/old-home.scss',
 
   // Vendor
   './h/static/styles/vendor/angular-csp.css',

h/static/styles/old-home.scss

+@at-root {
+  .press-release-banner {
+    background-color: #f7f7f7;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+  }
+
+  .press-release-banner > p {
+    font-size: 21px;
+    margin-top: 20px;
+    margin-bottom: 20px;
+    text-align: center;
+  }
+
+  /* FIXME: Remove the '!important' hack below and move
+  This to the correct stylesheet in the new homepage.
+   */
+  .social-media-link {
+    font-size: 16px !important;
+    text-decoration: none !important;
+  }
+}