styles.tsx

import * as React from "react";

import { StyleRules, withStyles, WithStyles } from "material-ui/styles";
import Typography from "material-ui/typography";

type ClassNames = "text";

const styles: StyleRules<ClassNames> = {
    text: {
        color: "blue"
    }
}

interface IProps {
    someText: string;
}

class MyComponent extends React.Component<IProps & WithStyles<ClassNames>> {
    public render() {
        return (
            <Typography type="body1" classes={{ root: this.props.classes.text }}>
                { this.props.someText }
            </Typography>
        );
    }
}

export default withStyles<ClassNames>(styles)<IProps>(MyComponent);