Not bad layout, Simple and clean for your eyes
About a 6/10 it can be some more detailed.
By the way, at the register, you used
<input name="username" type="text" id="username" onfocus= "this.style.backgroundColor='#D2D2D2';"
onblur="this.style.backgroundColor ='Window'; this.style.color='WindowText';" maxlength="20"><input maxlength=""> can be easily manipulated, I suggest you to use/add
if(strlen($_POST['username']) > 20)
{
die("<script type=\"text/JavaScript\">alert(\"Your username is longer than 20 characters\");</script>");
}And also for the other ones using $_POST['email'] and $_POST['password']
