This is an idea to help compare two HTML files which may have a lot of superficial differences but are structurally the same. Specifically, it's meant to reduce an HTML file to its essence... and reveal just the elements and classes

html_report.rb

require 'nokogiri'

failing = Nokogiri::HTML(File.read(ARGV.first))

def node_to_just_classes(node)
  {
    'name' => node.name,
    'classes' => (node.attributes["class"]&.value&.split(" ")&.compact || []),
    'children' =>  node.children.map { |child| node_to_just_classes(child) }
  }
end

just_classes = failing.children.map do |node|
  node_to_just_classes(node)
end

puts just_classes.to_yaml