message: refactor(gui): Add separating borders to file selector
  This adds thin gray borders to the control surfaces in
  the file selector for better visual distinction
  Change-Type: patch
diff: @@ -57,7 +57,8 @@ const Flex = styled.div`
  `
  const Header = Flex.extend`
  - margin: 10px 15px 0;
  + padding: 10px 15px 0;
  + border-bottom: 1px solid ${ colors.primary.faded };
  > * {
  margin: 5px;
  @@ -67,8 +68,9 @@ const Header = Flex.extend`
  const Main = Flex.extend``
  const Footer = Flex.extend`
  - margin: 10px 20px;
  + padding: 10px;
  flex: 0 0 auto;
  + border-top: 1px solid ${ colors.primary.faded };
  > * {
  margin: 0 10px;
  