chatbox problems

i am having problems with my chat box and making the forum transparent  i have the code in the css to change the @ to mod but is has not change it at all i don't now why can some one help he this is the code i put in

#chatbox > p span.user > span:after {
  content: '*';
}
#chatbox > p span.user > span strong {
  display:none; 
}
#chatbox_members li a > span:first-child strong { display:none; }
#chatbox_members li a > span:first-child:before { content: ' Moderator: '; }
a:link {

and this for the transparent part 
.bodyline {

    background-color: transparent !important;
    background-image: none !inportant;
    border: none !important;
 
help would be nice

The CSS for changing the '@' will not work in Phpbb2.