AO3-6749 Fix top-level menu item text color in Low Vision Default

Also adjust the selector for the text color of the site name in the header because it doesn't need to be so heavy

public/stylesheets/masters/low_vision_default/low_vision_default_site_screen_.css

@@ -136,18 +136,17 @@ pre {
 }
 
 #header,
-#header ul.primary,
 #header .open a,
-#header .open a:focus,
-#header .user .open a:focus,
+#header .primary .dropdown a:focus,
+#header .user .dropdown a:focus,
 #footer,
 .actions a:hover,
 .actions a:focus {
   background: #900;
   color: #eee;
 }
 
-#header h1.heading a {
+#header h1 a {
   color: #fff;
 }