Ktor CSS DSL

How can we make the following element green?

<h2 id="greeting">Hello, user!</h2>

1)

call.respondCss {
    rule("#greeting") {
        color = "#00FF00"
    }
}

2)

call.respondCss {
    rule(".greeting") {
        color = "#00FF00"
    }
}

3)

call.respondCss {
    rule("#greeting") {
        color = Color("#00FF00")
    }
}

4)

call.respondCss {
    rule(".greeting") {
        color = Color("#00FF00")
    }
}