'Block messages' string is too close to 'Send private message to @name' string

On users profiles 'Block messages' string is located too close just after to 'Send private message to @name' string. There is no empty line separating them. This causes users to accidentally press wrong button frequently. I tried to theme it in different ways like:

#block-message
.block-message
#privatemsg-block-message
.privatemsg-block-message

None of these worked. By the way css file of the module misses 'block-message' class, which is defined for this string in the module file. Can you please explain me how to make two strings to be placed in little bit more distance from each other.