the top border of the card was breaking the design of the tabs, where
the active tab would be "visually connected" to the content. also, the
rounded border at the top did not blend in with the navbar's bottom
border.
if the last child in a card (div.card > div.card-body) adds bottom
marging, we don't want the card to add more space through its
padding-bottom. most cards have children that add sufficient space
at the bottom anyways.
we don't need a margin at the bottom of tables in general. not sure why
this is even a thing in bootstrap. this change, in particular, makes the
space between a table and a parent card symmetric on all sides.
this change tries to achieve a pleasing look of input forms by
right-aligning the texts of labels. the input form now looks similar
to a table, achieving a cleaner look, especially for forms where the
labels have varying text lenghts.
