Home → References → CSS Properties →
CSS Property: counter-increment
Increments a named counter. Only supported by Opera at the time of writing.
HTML Dog, The Book 
HTML Dog is hosted by Titan Internet
Possible Values
inhertnone(default)- [name] [number] - the name of the counter optionally followed by the number that the counter should be increased by (default is 1). This can be a chain of names and numbers such as
chapter section 2which will increasechapterby 1 andsectionby 2.
Example
h3:before {
content: counter(section);
counter-increment: section;
}