<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>title</title> </head> <body> <p> <h1>hello</h1> <h2>hello</h2> <h3>hello</h3> <h4>hello</h4> <h5>hello</h5> <h6>hello</h6> </p> <p>h1到h5是标题标签，优先级依次递减，一般来说，一个页面只有一个h1</p> </body> </html>