### Config payment form

In mountPaymentElement function you can pass third config parameter.

```typescript
declare type TConfig = Partial<{
  theme?: "LIGHT" | "DARK" | "BROWSER";
  onResult?: (res: TResult) => void;
  onLoading?: (isLoading: boolean) => void;
  onTimeout?: () => void;
}>;
```

Property `theme` overrides theme type defined in back office, and you can call embedded form with dynamically changed theme.
Callback `onTimeout` will call when form time limit exceed. After timeout you need to remount component.
Callback `onLoading` will call every time the form starts or stops processing a payment.
Theme type `BROWSER` renders theme depending on system theme.

```javascript
upgate.mountPaymentElement("%elementId%", "%checkoutUrl%", { theme: "LIGHT" });
```