Breaking heading tags and inline CSS on pages

I believe I’m having the same issue as the previous person with the latest update. My registration page, login page and lost password page do not recognize any heading tags on the page with the plugin activated in firefox or Edge: https://stocktips.com/register but looks fine in chrome. I disabled all plugins and switched to 2015 theme and it is for sure this plugin. It also doesn’t recognize any inline cssk, ie, changing the style of a heading tag.

https://www.ads-software.com/plugins/theme-my-login/