Style Comment form headline/text

Hi, 

I want to change "# comments to …" and "Leave a Reply" to font-weight: normal (NOT bold)


I've added this code to CSS inserts. It works for '# comments to …'

but not for 'Leave a Reply'


h3#comments {
font-weight: normal;
}


h3.reply {
font-weight: normal;
}

Does anyone know where I'm going wrong?

Thanks