[Lynne]

If you only want it for admins, then replace my second box of code with:

<if condition="is_member_of($post, 6)">
<div id="post_message_$post[postid]" style="color: yellow;">
<else />
<div id="post_message_$post[postid]" style="color: blue;">
</if>

or

<if condition="is_member_of($post, 6)">
<div id="post_message_$post[postid]" style="color: yellow;">
<else />
<div id="post_message_$post[postid]">
</if>