Masterfully done, not much critique to give.
It just needs slightly more polish on the bullet visuals and hitboxes to get that perfect satisfying feel. Sometimes it felt like I should've either gotten hit or the bullet should've been parried but neither seemed to happen?
Also don't think the character should slow down while attacking but rather keep his momentum.
None of these really impact my score or enjoyment of the game.
The random bullets flying into the camera accentuating the invincibility of the character by making the camera more prone to damage was a great touch.
Great job!
P.S. I'm another data point in Firefox opening a menu on Shift + LMB