Hellow Mehraleo319 !
I couldn't find any policy forbidding that, but i guess it depends on how it impacts the "user experience".
If that box contains information that is forbidden by the Policy Rules, than it would not be ok.
Google allows even Flash Landing pages even if they do not provide the best "user experience"
and may require the installation of the plug-in and also may not be available for display on some smartphones, or they could load much slower than a html page.
There is an article about Understanding landing page experience that might help