html lang en-us или en-us
<!DOCTYPE html>
<html lang="en-US">
<!-- Specifies the document lauguage
(United States English) -->
</html>
Ugliest Unicorn
<!DOCTYPE html>
<html lang="en-US">
<!-- Specifies the document lauguage
(United States English) -->
</html><!DOCTYPE html>
<html lang="en"> <!-- sets language to english -->
<!-- <head>, <body>, etc. contents-->
</html>