Fitting section to cover page on all devices

Hi
I’ve created a ‘homepage’ that is actually a welcome page made up of a grid of flip boxes. This will be an initial portfolio for the client and when clicked, each box will take you to the relevant page. There is no header or footer and I just need the design to fix itself to the page size of any desktop device that sees it. Mobile and tablet, I will change for vertical viewing but I don’t want any type of border above or below the grid. Does anyone have any advice for me on how to achieve this?
Thanks

• This topic was modified 2 years, 11 months ago by Jan Dembowski. Reason: Moved to Fixing WordPress, this is not an Everything else WordPress topic
• This topic was modified 2 years, 11 months ago by James Huff.

The page I need help with: [log in to see the link]