I've just been notified that I have won the bronze mortarboard badge for earning at least 200 reputation in a single day.
Yet the same notification tells me I've earned just 199 reputation today.
How is this possible?
Reading the badge description here:
Earn at least 200 reputation (the daily maximum) in a single day.
Also, taking a look at your rep:
We can see that you already completed the requirements for the badge, that is earn at least 200 reps in a day. You earned 205 reps, which is sufficient condition for getting the badge. The -6 you got are not related, nor affect the badge condition.
In other words, if you made 400 reps in a day (just, imagine you do) but took -201 in downvotes (which gives a net number of 199) you still made at least 200 reps that day.
I've noticed a similar situation regarding the Rep Capping. I have in past days rep capped (+1 on my counter) by having +200/-1 , even though the net rep number was 199.