Along with sending an args object to your component, Streamlit also sends
a theme object defining the active theme so that your component can adjust
its styling in a compatible way. This object is sent in the same message as
args, so it can be accessed via this.props.theme (when using the React
template) or event.detail.theme (when using the plain TypeScript template).
The theme object has the following shape:
json
{
  "base": "lightORdark",
  "primaryColor": "someColor1",
  "backgroundColor": "someColor2",
  "secondaryBackgroundColor": "someColor3",
  "textColor": "someColor4",
  "font": "someFont"
}
The base option allows you to specify a preset Streamlit theme that your custom theme inherits from. Any theme config options not defined in your theme settings have their values set to those of the base theme. Valid values for base are "light" and "dark".
