Bug 1087015: Demo Stuido - gallery page

- Decreased max-width of the section
- Gallery page now stacks
- Replaced JS that created "card" effect on hover with pure CSS
- Revived background image on not-the-landing-page
- Restricted button styles to act within main content
- Decreased number of demos in a gallery to 10 so they don't leave 2 dangling on a max width screen.