[Accessibility] Manage focus on navigation (#39350)

app/javascript/styles/mastodon/components.scss

@@ -9146,6 +9146,8 @@ noscript {
     padding-bottom: 32px;
   }
 
+  h1,
+  h2,
   h3 {
     font-size: 22px;
     line-height: 33px;
@@ -9176,6 +9178,8 @@ noscript {
   &__lead {
     margin-bottom: 20px;
 
+    h1,
+    h2,
     h3 {
       margin-bottom: 15px;
     }
@@ -9251,6 +9255,8 @@ noscript {
       flex: 1;
       box-sizing: border-box;
 
+      h1,
+      h2,
       h3 {
         margin-bottom: 20px;
       }