Update header and footer

Author: mborland

doc/supplemental-ui/partials/footer-content.hbs

@@ -0,0 +1,2 @@
+<footer class="footer">
+</footer>

doc/supplemental-ui/partials/header-content.hbs

@@ -0,0 +1,50 @@
+<header class="header">
+  <nav class="navbar">
+    <div class="navbar-brand">
+      <a class="navbar-item" href="{{{or site.url siteRootPath}}}">{{site.title}}</a>
+      {{#if env.SITE_SEARCH_PROVIDER}}
+      <div class="navbar-item search hide-for-print">
+        <div id="search-field" class="field">
+          <input id="search-input" type="text" placeholder="Search the docs"{{#if page.home}} autofocus{{/if}}>
+        </div>
+      </div>
+      {{/if}}
+      <button class="navbar-burger" aria-controls="topbar-nav" aria-expanded="false" aria-label="Toggle main menu">
+        <span></span>
+        <span></span>
+        <span></span>
+      </button>
+    </div>
+    <div id="topbar-nav" class="navbar-menu">
+      <div class="navbar-end">
+        <a class="navbar-item" href="index.html">Home</a>
+    <!--
+        <div class="navbar-item has-dropdown is-hoverable">
+          <a class="navbar-link" href="#">Products</a>
+          <div class="navbar-dropdown">
+            <a class="navbar-item" href="#">Product A</a>
+            <a class="navbar-item" href="#">Product B</a>
+            <a class="navbar-item" href="#">Product C</a>
+          </div>
+        </div>
+    -->
+    <!--
+        <div class="navbar-item has-dropdown is-hoverable">
+          <a class="navbar-link" href="#">Services</a>
+          <div class="navbar-dropdown">
+            <a class="navbar-item" href="#">Service A</a>
+            <a class="navbar-item" href="#">Service B</a>
+            <a class="navbar-item" href="#">Service C</a>
+          </div>
+        </div>
+    -->
+        <div class="navbar-item">
+          <span class="control">
+            <a class="button is-primary" href="https://github.com/cppalliance/decimal/releases">Download</a>
+          </span>
+        </div>
+      </div>
+    </div>
+  </nav>
+</header>
+