content 속성

normal	Default value. Sets the content, if specified, to normal, which default is "none" (which is nothing)	Try it »
none	Sets the content, if specified, to nothing	Try it »
counter	Sets the content as a counter	Try it »
attr(attribute)	Sets the content as one of the selector's attribute	Try it »
string	Sets the content to the text you specify	Try it »
open-quote	Sets the content to be an opening quote	Try it »
close-quote	Sets the content to be a closing quote	Try it »
no-open-quote	Removes the opening quote from the content, if specified	Try it »
no-close-quote	Removes the closing quote from the content, if specified	Try it »
url(url)	Sets the content to be some kind of media (an image, a sound, a video, etc.)	Try it »
initial	Sets this property to its default value. Read about initial
inherit	Inherits this property from its parent element. Read about inherit

- counter

content요소가 들어가는 영역, 즉 ::before나 ::after를 떼고 난 선택자에 counter-increment: counterName; 을 붙인다.

가상요소를 붙인 곳에 content: counter(counterName);

1이 아닌 다른 숫자로 카운팅을 시작하고 싶으면 해당 영역을 선택하고 counter-reset: counterName startNumber;

증가값이 1이 아닌 경우, counter-increment: counterName incrementNumber;

counters도 업데이트 필요.