line 1 column 1 - Warning: missing <!DOCTYPE> declaration
line 4 column 1 - Warning: <span> missing '>' for end of tag
line 4 column 1 - Info: value for attribute "class" missing quote marks
line 4 column 1 - Warning: missing </span> before <p>
line 5 column 4 - Warning: inserting implicit <span>
line 6 column 1 - Warning: discarding unexpected </span>
line 4 column 1 - Warning: trimming empty <span>
Info: Document content looks like HTML5
Tidy found 6 warnings and 0 errors!

One or more empty elements were present in the source document but
dropped on output. If these elements are necessary or you don't want
this behavior, then consider setting the option "drop-empty-elements"
to no.

About HTML Tidy: https://github.com/htacg/tidy-html5
Bug reports and comments: https://github.com/htacg/tidy-html5/issues
Official mailing list: https://lists.w3.org/Archives/Public/public-htacg/
Latest HTML specification: https://html.spec.whatwg.org/multipage/
Validate your HTML documents: https://validator.w3.org/nu/
Lobby your company to join the W3C: https://www.w3.org/Consortium

Do you speak a language other than English, or a different variant of 
English? Consider helping us to localize HTML Tidy. For details please see 
https://github.com/htacg/tidy-html5/blob/master/README/LOCALIZE.md
