The CardView extends FrameLayout. This layout has some problems with
margins: http://stackoverflow.com/questions/5401952/framelayout-margin-not-working.
These can be overcome in most situations by swithcing from a margin to
some padding on the child view. The reason it is okay to do this in
most cases is because the child view is usually a layout such as a
ConstraintLayout anyway. For such cases, the difference between margin
and padding is not much different, because there are usually not any
background colours or borders applied (where padding vs margin would
usually make a difference).
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