Create a custom dark theme object by using the default dark theme as a base and applying overrides.
const defaultDarkTheme = darkTheme();const customTheme = darkTheme({  colors: {    modalBg: "red",  },});let returnType: {  colors: {    accentButtonBg: string;    accentButtonText: string;    accentText: string;    borderColor: string;    connectedButtonBg: string;    connectedButtonBgHover: string;    danger: string;    inputAutofillBg: string;    modalBg: string;    modalOverlayBg: string;    primaryButtonBg: string;    primaryButtonText: string;    primaryText: string;    scrollbarBg: string;    secondaryButtonBg: string;    secondaryButtonHoverBg: string;    secondaryButtonText: string;    secondaryIconColor: string;    secondaryIconHoverBg: string;    secondaryIconHoverColor: string;    secondaryText: string;    selectedTextBg: string;    selectedTextColor: string;    separatorLine: string;    skeletonBg: string;    success: string;    tertiaryBg: string;    tooltipBg: string;    tooltipText: string;  };  fontFamily: string;  type: "light" | "dark";};Theme object