import { Frame } from '@shopify/polaris';

// This does not set the width
const FrameWrapper = styled(Frame)`
  width: 50%;  
`;

// Instead create a wrapper component
const Wrapper = styled.div`
  width: 50%;  
`;

class Component {
  render() {  
    <Wrapper>
      <Frame {...props} />
    </Wrapper>;
  }
}