office-ui-fabric-core/src/data/type-weights.json

The front-end framework for building experiences for Office 365.

[
  {
    "name": "Regular",
    "weight": 400
  },
  {
    "name": "Semibold",
    "weight": 600
  },
  {
    "name": "Bold",
    "weight": 700
  }
]