Modal inside bx--content (Content component)

[alissa9090]

Title line template: [Title]: Brief description

Modal inside bx--content (Content component) is shown incorrectly

What package(s) are you using?

• carbon-components
• carbon-components-react ^7.29.0

Detailed description

Modal overlay is broken when its shown inside Content component with scrollable content. Looks like
transform: translate3d(0, 0, 0); from bx--content class is causing it.

Steps to reproduce the issue

1. Step one
   Create a Button and a Modal inside Content component

2. Step two
   put some text or other component above Modal so that you have to scroll to reach it.

3. Step three
   click the Button and show the Modal.

https://codesandbox.io/s/eager-lalande-rq5xy?file=/src/index.js

Additional information