$ bundle exec jekyll build -s spec/ -d build/spec
/home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/html.rb:10:in `require': cannot load such file -- rexml/parsers/baseparser (LoadError)
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/html.rb:10:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown/html.rb:10:in `require'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown/html.rb:10:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown/paragraph.rb:14:in `require'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown/paragraph.rb:14:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown.rb:345:in `require'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown.rb:345:in `<class:Kramdown>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown.rb:60:in `<module:Parser>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown.rb:19:in `<module:Kramdown>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/kramdown-1.17.0/lib/kramdown/parser/kramdown.rb:17:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll/converters/smartypants.rb:3:in `require'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll/converters/smartypants.rb:3:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll.rb:13:in `require'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll.rb:13:in `block in require_all'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll.rb:12:in `each'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll.rb:12:in `require_all'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/lib/jekyll.rb:189:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/exe/jekyll:8:in `require'
	from /home/travis/.rvm/gems/ruby-3.1.2/gems/jekyll-3.6.3/exe/jekyll:8:in `<top (required)>'
	from /home/travis/.rvm/gems/ruby-3.1.2/bin/jekyll:25:in `load'
	from /home/travis/.rvm/gems/ruby-3.1.2/bin/jekyll:25:in `<main>'
	from /home/travis/.rvm/gems/ruby-3.1.2/bin/ruby_executable_hooks:22:in `eval'
	from /home/travis/.rvm/gems/ruby-3.1.2/bin/ruby_executable_hooks:22:in `<main>'