Transparency on WinForms is impossible?

I've been trying lots of solutions to figure this out but it doesn't seem to work. How can i make this control transparent on background so it'll show the picturebox uigradient?

https://preview.redd.it/asqj6goe7xyd1.png?width=589&format=png&auto=webp&s=a0cf21597d14a1d6c8ea04f2a902b67ceb11eb69

What i've tried so far is adding SetStyle(ControlStyles.SupportsTransparentBackColor, true);
with protected override void OnPaintBackground(PaintEventArgs e) . It only makes the background black on transparent controls.