Impossible to centre [isell_download_page]

Hi there,

I would like to centre the text displayed on the download page but I can’t make it work.
My page have the following:

<p style=”text-align: center;”>[isell_download_page]</p>

The shortcode seems to add an iframe to the page that can’t be centred. Please let me know if there is a way to do this.

Thanks for your help.

https://www.ads-software.com/plugins/sell-digital-downloads/