fix: use a more specific CSS selector for navigation numbered lists (#75)

This allows unnumbered lists inside `nav` elements, that were previously
incorrectly numbered.

Author: vihuna

style.css

@@ -468,10 +468,10 @@ nav ol {
   counter-reset: item;
   padding-left: 2rem;
 }
-nav li {
+nav ol > li {
   display: block;
 }
-nav li::before {
+nav ol > li::before {
   content: counters(item, '.') ' ';
   counter-increment: item;
   padding-right: 0.85rem;