sure/app/views/layouts/application.html.erb

<% intro_mode = Current.user&.ui_layout_intro? %>
<% home_path = intro_mode ? chats_path : root_path %>
<% mobile_nav_items = if intro_mode
  [
    { name: t(".nav.home"), path: chats_path, icon: "home", icon_custom: false, active: page_active?(chats_path) },
    { name: "Intro", path: intro_path, icon: "sparkles", icon_custom: false, active: page_active?(intro_path) }
  ]
else
  [
    { name: t(".nav.home"), path: root_path, icon: "pie-chart", icon_custom: false, active: page_active?(root_path) },
    { name: t(".nav.transactions"), path: transactions_path, icon: "credit-card", icon_custom: false, active: page_active?(transactions_path) },
    { name: t(".nav.reports"), path: reports_path, icon: "chart-bar", icon_custom: false, active: page_active?(reports_path) },
    { name: t(".nav.budgets"), path: budgets_path, icon: "map", icon_custom: false, active: page_active?(budgets_path) },
    preview_gated_nav_item({ name: t(".nav.goals"), path: goals_path, icon: "piggy-bank", icon_custom: false, active: page_active?(goals_path) }),
    (preview_gated_nav_item({ name: t(".nav.retirement"), path: retirement_path, icon: "sun", icon_custom: false, active: page_active?(retirement_path) }) if Current.family.retirement_enabled?(Current.user)),
    { name: t(".nav.assistant"), path: chats_path, icon: "icon-assistant", icon_custom: true, active: page_active?(chats_path), mobile_only: true }
  ].compact
end %>

<% desktop_nav_items = mobile_nav_items.reject { |item| item[:mobile_only] } %>
<% expanded_sidebar_class = "w-full" %>
<% collapsed_sidebar_class = "w-0 overflow-hidden" %>

<%= render "layouts/shared/htmldoc" do %>
  <div
    class="flex flex-col lg:flex-row h-full bg-surface"
    data-controller="app-layout privacy-mode"
    data-app-layout-expanded-sidebar-class="<%= expanded_sidebar_class %>"
    data-app-layout-collapsed-sidebar-class="<%= collapsed_sidebar_class %>"
    data-app-layout-user-id-value="<%= Current.user.id %>">
    <%= link_to t("layouts.application.skip_to_main"), "#main",
        class: "sr-only focus:not-sr-only focus:fixed focus:top-2 focus:left-2 focus:z-50 focus:px-3 focus:py-2 focus:rounded-lg focus:bg-container focus:text-primary focus:shadow-border-xs" %>

    <div
      class="hidden fixed inset-0 bg-surface z-20 h-full w-full pt-[calc(env(safe-area-inset-top)+0.75rem)] pr-3 pb-[calc(env(safe-area-inset-bottom)+0.75rem)] pl-3 overflow-y-auto transition-all duration-300"
      data-app-layout-target="mobileSidebar">
      <% unless intro_mode %>
        <div class="mb-2">
          <%= icon("x", as_button: true, data: { action: "app-layout#closeMobileSidebar" }) %>
        </div>
      <% end %>

      <%= render(
        "accounts/account_sidebar_tabs",
        family: Current.family,
        active_tab: @account_group_tab,
        mobile: true
      ) %>
    </div>

    <%# MOBILE - Top nav %>
    <nav class="lg:hidden flex justify-between items-center p-3 pt-[calc(env(safe-area-inset-top)+0.75rem)]">
      <% if intro_mode %>
      <% else %>
        <%= icon("panel-left", as_button: true, data: { action: "app-layout#openMobileSidebar"}) %>
      <% end %>

      <%= link_to home_path, class: "block" do %>
        <%= image_tag "logomark-color.svg", class: "w-9 h-9 mx-auto" %>
      <% end %>

      <div class="flex items-center gap-1">
        <button type="button"
                class="inline-flex items-center justify-center w-8 h-8 rounded-lg text-secondary hover:text-primary transition-colors"
                data-action="click->privacy-mode#toggle"
                data-privacy-mode-target="toggle"
                title="<%= t("layouts.application.privacy_mode") %>"
                aria-label="<%= t("layouts.application.privacy_mode") %>"
                aria-pressed="false">
          <%= icon("eye-off", size: "sm", data: { privacy_mode_target: "iconOff" }) %>
          <%= icon("eye", size: "sm", class: "hidden", data: { privacy_mode_target: "iconOn" }) %>
        </button>
        <%= render "users/user_menu", user: Current.user, placement: "bottom-end", offset: 12, intro_mode: intro_mode %>
      </div>
    </nav>

    <%# DESKTOP - Left navbar %>
    <div class="hidden lg:block border-r border-divider">
      <nav class="h-full flex flex-col shrink-0 w-[84px] py-4">
        <div class="pl-2 mb-3">
          <%= link_to home_path, class: "block" do %>
            <%= image_tag "logomark-color.svg", class: "w-9 h-9 mx-auto" %>
          <% end %>
        </div>

        <ul class="space-y-0.5">
          <% desktop_nav_items.reject { |item| item[:mobile_only] }.each do |nav_item| %>
            <li>
              <%= render "layouts/shared/nav_item", **nav_item %>
            </li>
          <% end %>
        </ul>

        <div class="pl-2 mt-auto mx-auto flex flex-col gap-2">
          <%= render DS::Link.new(
            variant: "icon",
            icon: "message-circle-question",
            href: "https://discord.gg/36ZGBsxYEK",
            target: "_blank"
          ) %>

          <%= render "users/user_menu", user: Current.user, intro_mode: intro_mode %>
        </div>
      </nav>
    </div>

    <%# DESKTOP - Left sidebar %>
    <%= tag.div class: class_names(
        "hidden lg:block py-4 shrink-0 max-w-[320px] transition-all duration-300 border-divider",
        Current.user.show_sidebar? ? [expanded_sidebar_class, "border-r"] : [collapsed_sidebar_class, "border-r-0"],
       ),
       inert: !Current.user.show_sidebar?,
       data: { app_layout_target: "leftSidebar" } do %>
      <div class="px-4 h-full flex flex-col overflow-y-auto">
        <% if content_for?(:sidebar) %>
          <%= yield :sidebar %>
        <% else %>
          <div class="grow">
            <%= render "accounts/account_sidebar_tabs", family: Current.family, active_tab: @account_group_tab %>
          </div>

          <% if Current.family.trialing? && !self_hosted? %>
            <div class="px-4 py-3 space-y-4 bg-container shadow-border-xs rounded-xl">
              <div class="flex items-start justify-between">
                <div>
                  <p class="text-sm font-medium text-primary"><%= t("layouts.trial.open_demo") %></p>
                  <p class="text-sm text-secondary"><%= t("layouts.trial.data_deleted_in_days", days: Current.family.days_left_in_trial) %></p>
                </div>

                <%= render DS::Link.new(
                  text: t("layouts.trial.contribute"),
                  href: upgrade_subscription_path,
                ) %>
              </div>

              <div class="flex items-center gap-0.5 h-1.5">
                <div class="h-full bg-warning rounded-full" style="width: <%= Current.family.percentage_of_trial_completed %>%"></div>
                <div class="h-full bg-surface-inset rounded-full" style="width: <%= Current.family.percentage_of_trial_remaining %>%"></div>
              </div>
            </div>
          <% end %>
        <% end %>
      </div>
    <% end %>

    <%# SHARED - Main content %>
    <%= tag.main id: "main", class: class_names("grow overflow-y-auto px-3 lg:px-10 w-full mx-auto pb-[calc(5rem+env(safe-area-inset-bottom))] lg:pb-0"), data: { app_layout_target: "content", viewport_target: "content" } do %>
      <% unless intro_mode %>
        <div class="hidden lg:flex gap-2 items-center justify-between mb-6 sticky top-0 z-10 -mx-3 lg:-mx-10 px-3 lg:px-10 py-4 bg-surface border-b border-tertiary">
          <div class="flex items-center gap-2">
            <%= icon("panel-left", as_button: true, data: { action: "app-layout#toggleLeftSidebar" }) %>

            <% if content_for?(:breadcrumbs) %>
              <%= yield :breadcrumbs %>
            <% else %>
              <%= render "layouts/shared/breadcrumbs", breadcrumbs: breadcrumbs %>
            <% end %>
          </div>

          <div class="flex items-center gap-2">
            <button type="button"
                    class="inline-flex items-center justify-center w-8 h-8 rounded-lg text-secondary hover:text-primary hover:bg-surface-hover transition-colors"
                    data-action="click->privacy-mode#toggle"
                    data-privacy-mode-target="toggle"
                    title="<%= t("layouts.application.privacy_mode") %>"
                    aria-label="<%= t("layouts.application.privacy_mode") %>"
                    aria-pressed="false">
              <%= icon("eye-off", size: "sm", data: { privacy_mode_target: "iconOff" }) %>
              <%= icon("eye", size: "sm", class: "hidden", data: { privacy_mode_target: "iconOn" }) %>
            </button>

            <%= icon("panel-right", as_button: true, data: { action: "app-layout#toggleRightSidebar" }) %>
          </div>
        </div>
      <% end %>

      <% if content_for?(:page_header) %>
        <%= yield :page_header %>
      <% end %>

      <%= yield %>
    <% end %>

    <%# DESKTOP - Right sidebar %>
    <%= tag.div class: class_names(
          "hidden lg:block h-full shrink-0 max-w-[400px] transition-all duration-300 border-divider",
          Current.user.show_ai_sidebar? ? [expanded_sidebar_class, "border-l"] : [collapsed_sidebar_class, "border-l-0"],
        ),
        inert: !Current.user.show_ai_sidebar?,
        data: { app_layout_target: "rightSidebar" } do %>
      <%= tag.div id: "chat-container", class: "relative h-full px-4 overflow-y-auto", data: { controller: "chat hotkey", turbo_permanent: true } do %>
        <div class="flex flex-col h-full justify-between shrink-0">
          <%= turbo_frame_tag chat_frame, src: chat_view_path(@chat), loading: "lazy", class: "h-full" do %>
            <div class="flex justify-center items-center h-full">
              <%= icon("loader-circle", class: "animate-spin") %>
            </div>
          <% end %>
        </div>

        <% unless Current.user.ai_enabled? %>
          <div class="absolute backdrop-blur-lg inset-0 h-full w-full flex flex-col justify-center items-center px-4">
            <%= render "chats/ai_consent" %>
          </div>
        <% end %>
      <% end %>
    <% end %>

    <%# MOBILE - Bottom Nav %>
    <%= tag.nav class: "lg:hidden fixed bottom-0 left-0 right-0 bg-surface z-10 border-t border-tertiary flex justify-around pb-[env(safe-area-inset-bottom)]",
      data: { viewport_target: "bottomNav" } do %>
      <% mobile_nav_items.each do |nav_item| %>
        <%= render "layouts/shared/nav_item", **nav_item %>
      <% end %>
    <% end %>
  </div>
<% end %>