Add .vh (visually hidden) CSS class styling

main.css

@@ -45,6 +45,16 @@ position:absolute;overflow:hidden;
 left:-9999px;top:auto;
 width:1px;height:1px;
 }
+.vh{
+position:absolute;
+clip:rect(1px,1px,1px,1px);
+height:1px;width:1px;
+padding:2px 8px;overflow:hidden;
+white-space:nowrap;
+background:#FFF}
+.vh:focus{
+clip:auto;overflow:auto;
+height:auto;width:auto}
 footer p{margin:0}
 
 table{text-align:left;width:100%;