$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;