Samsung Android Web Browser & CSS Border-Radius property
Basically, if you use border-radius anywhere in your CSS, the native Android web browser on this device ignores it. But if you use the long-form CSS property of border-right-radius, border-left-radius, etc, it recognizes it. In essence, part of the base CSS3 support is broken in this browser for rounded borders. Other Android web browsers (including the Galaxy SIII) in other devices properly handle this CSS rule.
This is a bug in the browser itself.