Different background for each post in a categoary

Hi

I’ve managed to put a different background on a category page by editing the header.php to use a simple else / if command for 2 different stylesheets. But what I really want is for each page in that category to display the alternate stylesheet as well. How do I achieve this?

The site is: https://www.luv4arts.co.uk
The alt. category is: https://www.luv4arts.co.uk/category/luv-4-arts-jamaica/

Many thanks!