These settings affect the Login Panel.

"format": {
  "fonts": {
    "logInFieldsetTitle": {"name": "Avenir-Light", "size": 16},
    "usernameField": {"name": "Avenir-Light", "size": 16},
    "passwordField": {"name": "Avenir-Light", "size": 16}
    },
  "colors": {
    "logInFieldsetBackground": [125, 125, 125, 1.0],
    "logInFieldsetBorder": [125, 125, 125, 1.0],
    "logInFieldsetTitle": [125, 125, 125, 1.0],
    "usernameFieldBackground": [125, 125, 125, 1.0],
    "usernameFieldText": [125, 125, 125, 1.0],
    "usernameFieldBorder": [125, 125, 125, 1.0],
    "passwordFieldBackground": [125, 125, 125, 1.0],
    "passwordFieldText": [125, 125, 125, 1.0],
    "passwordFieldBorder": [125, 125, 125, 1.0],
    "usernameFieldPlaceholderText": [125, 125, 125, 1.0],
    "passwordFieldPlaceholderText": [125, 125, 125, 1.0],
    "panelCloseButton": [125, 125, 125, 1.0],
    "panelCloseButtonHighlight": [125, 125, 125, 1.0],
    "buttonLogInBackground": [125, 125, 125, 1.0],
    "buttonLogInSelected": [125, 125, 125, 1.0],
    "buttonLogInBorder": [125, 125, 125, 1.0],
    "buttonLogInText": [125, 125, 125, 1.0]
    },
  "dimensions": {
    "logInFieldsetBorderSize": 1,
    "logInFieldsetBorderRadius": 1,
    "usernameFieldHeight": 40,
    "usernameFieldMinimumFontSize": 16,
    "usernameFieldBorderSize": 1,
    "usernameFieldBorderRadius": 1,
    "passwordFieldHeight": 40,
    "passwordFieldBorderSize": 1,
    "passwordFieldBorderRadius": 5,
    "buttonLogInBorderSize": 1,
    "buttonLogInBorderRadius": 5
   	},
  "padding": {
    "usernameFieldPadding": [5, 5, 5, 5],
    "passwordFieldPadding": [5, 5, 5, 5],
    "buttonLogInPadding": [5, 5, 5, 5]
    },
  "positions": {
    "logInFieldsetTitleAlignment": 1,
    "usernameFieldTextAlignment": 1,
    "passwordFieldTextAlignment": 1
    }
  }