Fix nav item vertical alignment: center all items in flex row and their children

Author: jbonofre

docs/assets/stylesheets/global.css

@@ -285,12 +285,18 @@ h6, .h6, .md-typeset h6 {
 
 .md-header__nav {
   display: flex;
+  align-items: center;
   list-style: none;
   margin: 0;
   padding: 0;
   gap: 1.5rem;
 }
 
+.md-header__nav-item {
+  display: flex;
+  align-items: center;
+}
+
 .md-header__nav-link {
   color: var(--ossie-gray-700);
   font-size: 0.75rem;