These settings affect the Registration Email & Form.

"format": {
  "colors": {
     "registerHeaderBackgroundColor": [208, 2, 27, 1],
     "registerTextColor": [245, 166, 35, 1],
     "registerBackgroundColor": [248, 231, 28, 1],
     "registerFieldTextColor": [139, 87, 42, 1],
     "registerFieldBackgroundColor": [126, 211, 33, 1],
     "registerFieldBorderColor": [65, 117, 5, 1],
     "registerFieldButtonTextColor": [189, 16, 224, 1],
     "registerFieldButtonBackgroundColor": [144, 19, 254, 1],
     "registerFieldButtonBorderColor": [74, 144, 226, 1]
    }
  }