Need help on CSS to fix table vertical centering in my pages

Most WP themes bring in CSS that messes up the vertical centering in tables that I have in my pages, including MH lite that I really like. Tortuga Lite is an exception, but I do not like that theme. I need to know how I can override whatever the themes are doing that is affecting my tables. See https://www.rtbaileyphd.com/testpageonly for a complete explantion. An iframe would work if I included the CSS, but I don’t want to use iframes because I think it will mess up the Google indexing. I think if I knew the right CSS, I could include it in the head of all pages using the per-page-add-to-head widget, but I don’t know what CSS to use. Please help me.