What are the default font sizes (in pixels) for the html heading tags (

Question

What are the default font pixel sizes for the heading (h1-h6) tags?

Answer 1

For an actual proof, take a look at the html.css (171 - 237) with the default style of Mozilla Firefox:

h1 {
  font-size: 2em;
}

h2 {
  font-size: 1.5em;
}

h3 {
  font-size: 1.17em;
}

h4 {
  font-size: 1.00em;
}

h5 {
  font-size: 0.83em;
}

h6 {
  font-size: 0.67em;
}

The whole css is:

h1 {
  display: block;
  font-size: 2em;
  font-weight: bold;
  margin-block-start: .67em;
  margin-block-end: .67em;
}

h2,
:-moz-any(article, aside, nav, section)
h1 {
  display: block;
  font-size: 1.5em;
  font-weight: bold;
  margin-block-start: .83em;
  margin-block-end: .83em;
}

h3,
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
h1 {
  display: block;
  font-size: 1.17em;
  font-weight: bold;
  margin-block-start: 1em;
  margin-block-end: 1em;
}

h4,
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
h1 {
  display: block;
  font-size: 1.00em;
  font-weight: bold;
  margin-block-start: 1.33em;
  margin-block-end: 1.33em;
}

h5,
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
h1 {
  display: block;
  font-size: 0.83em;
  font-weight: bold;
  margin-block-start: 1.67em;
  margin-block-end: 1.67em;
}

h6,
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
:-moz-any(article, aside, nav, section)
h1 {
  display: block;
  font-size: 0.67em;
  font-weight: bold;
  margin-block-start: 2.33em;
  margin-block-end: 2.33em;
}