line 25 column 5 - Info: detected autonomous custom tag <new-tag>; will treat as block level
line 13 column 3 - Warning: <li> attribute "is" lacks value
line 14 column 3 - Warning: <li> attribute "is" lacks value
line 15 column 3 - Warning: <li> attribute "is" has invalid value "custom_element"
line 16 column 3 - Warning: <li> attribute "is" has invalid value "custom-element me_too"
line 22 column 5 - Warning: <jets-pizza> attribute "is" not allowed for autonomous custom tags.
line 25 column 5 - Warning: <new-tag> attribute "is" not allowed for autonomous custom tags.
line 19 column 5 - Warning: <pizzerias> is not approved by W3C
Info: Document content looks like HTML5
Tidy found 7 warnings and 0 errors!

About HTML Tidy: https://github.com/htacg/tidy-html5
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