The Android-WebKit-Browser seems to add a special overlay box to the input type "password" on focus (I think to apply this special mobile masking where the last letter typed is still visible) which ignores all styling except the "-webkit-tap-highlight-color" property.
So you will be out of luck styling these input boxes. Btw. styling of input boxes doesn't work at all on devices with HTC Sense, have a look here:
Input-Elements in WebViews always have the same style if highlighted on HTC Devices
Oh, one exception: the stylings seem to work on samsung devices (at least on Galaxy S and I5800)
