Add ':focus' style to show the focus-ring for <a> tags in demo center.

Author: jeonghee27

demo/style.css

@@ -19,6 +19,10 @@ body {
   word-break: break-word;
 }
 
+:focus {
+  outline: 2px solid #1E90FF;
+}
+
 /* style for side menu area */
 nav {
   font-family:'LG Smart';