Answers for "how to add bottstrap to html"

roll back last commit in git

git reset --soft HEAD~1

github restore previous commit

# syntax
git revert <commit>
# example
git revert 99a5c5905e12c74725bae64c61efce140662ce24
# where 99a5c59... is the commit (you can check it on github)

bootstrap cdn

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">