Random Background in pages
I have been looking all over the internet for an answer to my question. Have come close in finding it but to no avail. (:
Here is what I want to do. I have a site with over 300 videos, with each one having its own html to play in an embedded player. I use css to format the pages for a table around the player, and formatting of the text on the pages. I would like to have a way for it to apply different backgrounds when someone plays a video. So basically with 300+ pages linked back to one css and with 7 background images available to those 300+ pages, how can i have the one css change the background randomly when a video page is opened? I want to do this so I don't have to edit 300+ pages LOL. I use Arles to generate the pages and the css file by the way. So I only want to edit the one css file. Also, I don't want a header, border, or table image, just a plain background tiled. PHP and CSS code will be most welcomed!! Thanks in advance for anyones assistance.
p.s. help with what to do with the code would be most appreciated also hehe... very new to css and totally new to php