AO3-6737 Make index clear nav in Low Vision Default when no landmark is present (#5083)

AO3-6737 Make listings clear navigation in Low Vision Default when no landmark is present

Author: sarken

public/stylesheets/masters/low_vision_default/low_vision_default_site_screen_.css

@@ -69,6 +69,10 @@ form blockquote.userstuff {
   border: 2px solid;
 }
 
+ul.navigation + .index {
+  clear: both;
+}
+
 li.blurb,
 .group {
   visibility: visible;