amadeu

I believe it depends on which is the parent element of the class “site” and how is its height set.

If the parent element (maybe body) is set to height: 100%, you could apply to .site -> min-height: 100%

I am not an expert in this field, but I think it should work if I understood it correctly.

Good luck! Let us know how it ended!

What do you mean by full-height?
Do you mean 100% height of the browser window?

Maybe this hepls: WordPress Backups

If you are familiar with FTP and WordPress structure, you could download a copy of the theme files.

Maybe your host provider offers backups or is already doing it.

And there are several plugins that will help with backups (Example: updraftplus)

I hope it helped!

Remember to backup your site before any update, just in case something do change.

I presume it could be different reasons. I am not such an expert in this topic.

I would start checking that the database is created properly with an user, and check you entered that information correctly during the installation.

What is showing when the error occurs?

(Maybe you find useful this article from wpbeginner )

Could you specify how are you trying to install it and where?