System Fonts

font-family: 
  system-ui, 
  -apple-system, 
  BlinkMacSystemFont, 
  "Segoe UI", 
  Roboto, 
  Oxygen, 
  Ubuntu, 
  Cantarell, 
  "Open Sans", 
  "Helvetica Neue", 
  sans-serif;

font-family: 
  ui-serif, 
  Georgia, 
  Cambria, 
  "Times New Roman", 
  Times, 
  serif;

font-family: 
  ui-monospace, 
  SFMono-Regular, 
  Menlo, 
  Monaco, 
  Consolas, 
  "Liberation Mono", 
  "Courier New", 
  monospace;