Don't use border-radius with a box-shadow blur on buttons

[bowenli]

The softening of the corner when a box-shadow blur is used gives the visual appearance of a larger than 2px border-radius for buttons.

I propose dropping the border-radius on buttons with box-shadow - which will be closer in appearance to the 2px border-radius that we have on other elements.

[bia]

The difference is almost not noticeable. I would stick with 2px.