Basic HTML and HTML5: Declare the Doctype of an HTML Document

My code does not work
this link for projcet:

<!DOCTYPE html>
<h1>A cat</h1>
1 Like

define your html tag before the h1 tag
also close the h1 tag which has been defined between html tag

<!DOCTYPE html>
<h1>Jingle Balls</h1>

It doesn't work when done correctly...
Jingle Balls

Jingle Balls

This is the correct way

Cat Lover

A cat

Correct Way