baseLineHeights top-level property Null safety

Implementation

NBLineHeights baseLineHeights = NBLineHeights(
  i2xs: 16.0,
  xs: 18.0,
  sm: 20.0,
  md: 22.0,
  lg: 24.0,
  xl: 28.0,
  i2xl: 32.0,
  i3xl: 40.0,
  i4xl: 48.0,
  i5xl: 65.0,
);