First row below the header in Primer::Beta::Box has rounded corners

[HDinger]

Version

0.19.0

Steps to reproduce

• Use a Primer::Beta::BorderBox like defined here: https://view-components-storybook.eastus.cloudapp.azure.com/view-components/lookbook/inspect/primer/beta/border_box/default
  • Take care, that there is at least one header and one row

e.g.

render(Primer::Beta::BorderBox.new) do |component|
  component.with_header { "Header" }
  component.with_body { "Body" }
  component.with_row { "Row one" }
  component.with_row { "Row two" }
end

Actual behavior

• The row has additional round corners at the top which looks weird because the header (or the body) is directly at the top:

• This becomes especially obvious in the high contrast themes
• The same issue appears when there is a body used but no footer:

Expected behavior

• There should be no rounded corners if a header (or a body) is defined.