What do these CSS definitions mean?

[fleefeFrorI]

A website I was perusing had some CSS definitions that look liked this:\[code\]#intro, #code { ... }#intro { ... }#code { ... }\[/code\]I've never seen this before. Two questions:[*]In the first case, is it defining both \[code\]#intro\[/code\] and \[code\]#code\[/code\] with thesame initial definition?[*]Are the subsequent definitions for \[code\]#intro\[/code\] and \[code\]#code\[/code\] additive to the original?