$header-height: 100px;
$footer-height: 35px;

.App {
  min-height: 100%;
  display: flex;
  flex-direction: column;
  align-content: stretch;
  margin: 1rem 0;

  .Header {
    flex: 0 0 $header-height;
  }
  .Body {
    flex: 1 1 calc(100% - #{$header-height} - #{$footer-height});
  }
  .Footer {
    flex: 0 0 $footer-height;
  }
}