body {counter-reset: section; }

h2 {padding-top: 2em; counter-increment: section; counter-reset: subsection;}

h2:before {content: counter(section) ". ";}

h3 {padding-top: 1em; }

p { padding-left: 0.8em; }

h3 {counter-reset: subsubsection;}

h3:before {
    content: counter(section) "." counter(subsection) ". ";
    counter-increment: subsection;
}

h4:before {
    content: counter(section) "." counter(subsection) "." counter(subsubsection) ". ";
    counter-increment: subsubsection;
}