Fix mobile view for address page

apps/block_scout_web/assets/css/_helpers.scss

@@ -46,3 +46,9 @@
 .pre-wrap {
   white-space: pre-wrap;
 }
+
+.mb-2-desktop {
+  @include media-breakpoint-up(sm) {
+    margin-bottom: .5rem !important;
+  }
+}

apps/block_scout_web/lib/block_scout_web/templates/address/overview.html.eex

@@ -38,7 +38,7 @@
             <% true -> %>
               <%= nil %>
           <% end %>
-          <h1 class="card-title lg-card-title mb-2">
+          <h1 class="card-title lg-card-title mb-2-desktop">
             <div class="title-with-label"><%= address_title(@address) %> <%= gettext "Details" %></div>
             <% validator_metadata = primary_validator_metadata(@address) %>
             <%= if contract?(@address) do %>