CSS counter-increment

Also see the full, alphabetical list of CSS properties

The CSS counter-increment property assists in generating automatic numbering (for example, Heading 1, Section 1.1, Heading 2, Heading 2.2 etc) by incrementing the count by a given number. The counter-increment property is used in conjunction with the CSS count() function of the 'content' property (which is used with the ':before' or ':after' pseudo-elements).

Also see the counter-reset and content properties.

h1:before {
    content: "Section " counter(section) " ";
    counter-increment: section;
}

Also see all CSS properties listed alphabetically