Material UI Dialog Component is not responsive and can't see all screen #331

Bug Report 🐛

I'm testing a Material UI Dialog and when opening the screen on playground the CSS is not applied and the screen size is not responsive not allowing to see the entire component

To Reproduce ✔️

1. Create a simple component like in Material UI Dialog document https://material-ui.com/components/dialogs/#simple-dialogs
2. Write a test to open the dialog and print the testing playground url
   https://codesandbox.io/s/frosty-cherry-k1gx8?file=/src/__tests__/GenericDialog.test.tsx
3. Access the url and only can see a large image without scroll options

Expected behavior 🤔

Open the playground and see the screen with images in standard sizes

Suggested solution 🔦

I believe that the cause is not applying a css on screen, this way images are not resized.

Your Environment 💻

• browser: Chrome
• os: Mac