Posts look odd and are not formatted correctly.

Starting today my posts began looking odd and are not formatted correctly. I am not sure if this is something I did, or if this is a bug with the theme, but the theme has worked beautifully until now. Please let me know how I can change this. Here is a link to my post: https://samitographi.com/the-oldest-public-library-of-the-americas/ See the header and the format is just off.