Are there standards for making a templates before selling?

Hello guys am wondering if there are standards for html templates ? I mean for example should I divide my html pages into smaller parts so when users buy them here they can require the smaller parts in PHP like requiring the header,body,footer which also means I need to create a css file for each of them or is it okay to design the whole page as one and for each page has its own design and upload it.

Yes, there’s. Just purchase and download one and check the coding and everything.
At the moment, there’s one free HTML theme, go to ThemeForest mainpage and scroll down till you find free “Grab this month’s freebies from across Envato Market” and download it for free.

Ok thanks I will check it.