count the number of unique html errors: http://validator.w3.org/
How to upload files into file inputs ?
Select the element and call the send_keys() method passing the file path, either the path relative to the test script, or an absolute path. Keep in mind the differences in path names between Windows and Unix systems.
count the number of unique css errors: https://jigsaw.w3.org/css-validator/
count the number of unique classes, and the number of ids
list the unique classes and ids used, for further inspection
check to see if width, height, style, or align attributes are used inside of the HTML
count the number of times you encounter a div with only a single child (even if that child has grand-children)