import * as React from "react"; import { styled } from "baseui"; import { Theme } from "baseui"; type CustomTheme = Theme & { extraProp: string }; const BlueDiv = styled<"div", { $color: keyof Theme["colors"] }, CustomTheme>( "div", ({ $color, $theme }) => ({ color: $theme.colors[$color], }), ); export default function Example() { return This is a blue div; }