update btn color for AAA a11y

Author: rpearce

docs/index.html

@@ -34,7 +34,7 @@
       .btn--words {
         display: inline-block;
         padding: 0.5em 1em;
-        background-color: #0099ff;
+        background-color: #005C9A;
         color: #fff;
         cursor: default;
         border-radius: 3px;