$font-stack-system:
  -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial,
  sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
$font-stack-georgia: "Georgia", "Cambria", "Times New Roman", "Times", serif;
$font-stack-helvetica:
  "Helvetica Neue", "Helvetica", "Roboto", "Arial", sans-serif;
$font-stack-monospace:
  "Bitstream Vera Sans Mono", "Consolas", "Courier", monospace;