add example for color schemes

layouts/partials/site-footer.html

@@ -1,8 +1,9 @@
 <footer class="gdoc-footer">
-    <div class="container">
-        <div>
+    <div class="container flex">
+        <span>
             Build with <a href="https://gohugo.io/" class="gdoc-footer__link">Hugo</a> and
             <svg class="icon heart"><use xlink:href="#heart"></use></svg>
-        </div>
+        </span>
+        <span>
     </div>
 </footer>

layouts/shortcodes/button.html

@@ -10,6 +10,8 @@
     {{ $ref = relref $ . }}
 {{ end }}
 
-<a {{ with $ref }} href="{{.}}" {{ end }} {{ with $target }} target="{{.}}" {{ end }} class="gdoc-btn{{ with .Get "class" }} {{ . }}{{ end }}">
+<span class="gdoc-button{{ with .Get "class" }} {{ . }}{{ end }}">
+<a {{ with $ref }} href="{{.}}" {{ end }} {{ with $target }} target="{{.}}" {{ end }} class="gdoc-button__link">
     {{ $.Inner }}
 </a>
+</span>