使用CSS3内置计数器功能，实现自动编号；

核心代码

body {counter-reset: section;
}h1 {counter-reset: subsection;
}h1:before {content: "Section " counter(section) ". ";counter-increment: section;
}h2:before {counter-increment: subsection;content: counter(section) "." counter(subsection) " ";
}

测试

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效果图