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<!DOCTYPE html> <html> <head> <style> h1 { counter-increment: section; } h1::before { content: "Section " counter(section) " "; } </style> </head> <body> <h1>HTML Tutorial</h1> <h1 id="myH1">CSS Tutorial</h1> <h1>JavaScripts Tutorial</h1> <p>Click the "Try it" button to change the counterIncrement of the second H1 element:</p> <button onclick="myFunction()">Try it</button> <script> function myFunction() { document.getElementById("myH1").style.counterIncrement = "subsection"; } </script> </body> </html>