I appreciate this post! I was hoping you would add an inline CSS style sheet to take care of the broken defaults. I only remember one off the top of my head, the rule for monospace font size. You need something like:
   code, pre, tt, kbd, samp {
     font-family: monospace, monospace;
   }
Paired with H5BP you can use Normalize.css (as an alternative to a reset like http://meyerweb.com/eric/tools/css/reset/) found at https://github.com/necolas/normalize.css/blob/master/normali...
There's also this short reset: https://www.joshwcomeau.com/css/custom-css-reset/