numbering.css

h1 {
  /* must reset here */
  counter-reset: chapter {{ page.chapter }};
}
h1:before {
  /* and must reset again here */
  counter-reset: chapter {{ page.chapter }};
  content: "Chapter " counter(chapter);
  display: block;
}

h2 {
  /* must increment here */
  counter-increment: section;
  counter-reset: subsection;
}
h2:before {
  /* and must reset again here */
  counter-reset: chapter {{ page.chapter }};

  content: counter(chapter) "." counter(section) ;
  display: inline;
  margin-right: 1em;
}
h2:after {
  /* can only have one counter-reset per tag, so can't do it in h2/h2:before... */
  counter-reset: example;
}

h3 {
  /* must increment here */
  counter-increment: subsection;
}
h3:before {
  /* and must reset again here */
  counter-reset: chapter {{ page.chapter }};

  content: counter(chapter) "." counter(section) "." counter(subsection);
  display: inline;
  margin-right: 1em;
}
h3[id*='example'] {
  /* must increment here */
  counter-increment: example;
  display: inline;
}
h3[id*='example']:before {
  /* and must reset again here */
  counter-reset: chapter {{ page.chapter }};

  content: "Example " counter(chapter) "." counter(section) "." counter(example);
  display: inline;
  margin-right: 1em;
}

.no-numbering, .no-numbering:before, .no-numbering:after {
  content: normal;
  counter-reset: none;
  counter-increment: none;
}