Change Individual Page Background - Lange

Site URL: http://www.billydupee.co.uk

Hi there, I am using the Lange template and I want to change the background of my Info page to Black, then use white text here. I have added in this code below which I found from the forum, however, it changes the background of all pages and also the header. 

body#collection-5d18349a84a155000110af0c #site {
   background: #000000;
}

Can I use custom CSS to change just the background of this page to black, but not the header - so keeping the header white as on the rest of the site. I have highlighted the section I want to change specifically on this page in red on the screen shot below.

Thanks

Can you share link to page in screenshot?

Sure, here you go: https://www.billydupee.co.uk/info

Add to Info page Settings > Advanced Header

<style>
  main#page {
    background: red;
}
</style>