Where am I gaining 6px height retrieving buddypress avatar [closed]

The problem is with your line heights being set at 1.5.

You need to set this in your CSS:

#avatar {
    line-height: 0;
}

Also, if you want to get your other buttons “Logout” and the username, you will need to set the specific height on the parent DIV, which should be 50px, being as though your image is 30px, and you have 10px padding on top and bottom