From reading around it seems the simplest solution would be to create a new theme, a new page, and apply that theme to that one page. My question is - if that is the best route - what is the minimum I would need to do to get that working?
I've read that the minimum requirements for a Wordpress theme are a
style.css with a header comment, and an
index.php. I'm wondering, could I simply save my HTML file as
index.php, without it containing any actual PHP code, and deploy it that way? Or perhaps I need to save it as
page.php and leave the
index.php as the default minimal code? Are there any requirements beyond having those two files?
Also, since I have been given full admin access to their site, and my first priority is not to mess with it in any way, is there anything I should bear in mind to ensure my theme doesn't interfere with the rest of the site?