<Button android:minHeight="0dp" android:minWidth="0dp" ...
References
https://stackoverflow.com/questions/17960599/how-to-remove-padding-around-buttons-in-android
<Button android:minHeight="0dp" android:minWidth="0dp" ...
References
https://stackoverflow.com/questions/17960599/how-to-remove-padding-around-buttons-in-android