In various examples on the internet I have found that they sometimes use :before and other times ::before
div::before {
content: 'bla ';
}
div:before {
content: 'bla ';
}
I've tried both of them and they always work for me, so I don't understand if there is any difference (or not), or which of the two I should use, or if it doesn't really matter and I can use both in any situation.