Ixion: Tidy up styles -- if the visibility hidden isn't needed, neither is the style making it visible again. See #498.

ixion/style.css

@@ -1758,7 +1758,6 @@ object {
 .site-header .search-field:focus {
 	width: 300px;
 	transition: 0.3s ease;
-	visibility: visible;
 }
 .site-header .search-form:hover .search-form-icon:before,
 .site-header .search-field:focus + .search-form-icon:before {