Just copy and paste each individual section where needed.

• the boxed layout uses custom Css with media queries.
• in order to only impact the section, this CSS is placed at section level (Advanced > Custom Css)
  
  
• if you want to build a page with a boxed-layout applied to the whole page, remove the css from this section, and place it at the page level, click the gear icon at the bottom left of the page (Page Settings > Custom Css)
  
  
• if you want to build a website with a boxed-layout applied everywhere, remove the css from this section, and place it at the global level – found by clicking the hamburger icon in the top left corner (Site Settings > Custom Css) AND replace “selector” in the code by “body“