In the dictionary: at all
used in negative statements and questions to emphasize what you are saying
They’ve done nothing at all to try and put the problem right.
He’s not looking at all well.
‘Do you mind if I stay a little longer?’ ‘No, not at all.’
Has the situation improved at all?
But people do say "But many people think it is sad that she wanted to change her appearance at all." which is a positive sentence
Why do they use "at all" in positive sentences?