Automatic width calculation of ActionMenu inside Dialog is broken

[HDinger]

Steps to reproduce

• Create a Primer::Alpha::Dialog
• Inside the dialog create a Primer::Alpha::ActionMenu
• Open the dialog and open the menu inside it

    <%= render(Primer::Alpha::Dialog.new(title: "Test")) do |d|
      d.with_show_button { button_text }
      d.with_body do
        render(Primer::Alpha::ActionMenu.new(anchor_align: :end,
                                             select_variant: :single,
                                             )) do |menu|
          menu.with_show_button() do |button|
            button.with_trailing_action_icon(icon: "triangle-down")
            "Open me"
          end
          menu.with_item(label: "Item 1")
          menu.with_item(label: "Item 2")
          menu.with_item(label: "Item 3")

        end

      end
    end %>

Actual behavior

• The dropdown of the menu is way too large
• This happens because the dialog sets --overlay-width: _{{xy}}_ px;. And the ActionMenu uses the same variable for its own width calulation

• This gets evn more bad, the larger the dialog itself is:

Expected behavior

• The automtic width calucation should also be working inside a dialog

[jonrohan]

Ahh, nice catch. It seems like the top Dialog's CSS variable is overriding the Menu's variable? Pull request welcome if you spot a quick fix. ❤