Post background and footer don't extend with content

The post background and footer don’t extend with the content. The content continues below the footer. Also the previous/ next post links overlap with the content. I have been trying to find where the error is in the css, but honestly do not know enough to identify where the issue is. Here is a link to our website that shows the issue:

https://frenchlegationmuseum.org/summer-saturdays-family-fun-at-the-french-legation-museum/