Code snippet fade effect is inconsistent in Safari

[sltclss]

What package(s) are you using?

Mac os Catalina 10.15.1
Safari 13.0.3
carbon-components 10.7.4
carbon-components-react 7.7.4

Detailed description

The ::after pseudo element of the code snippets are a dark gray.

Is this issue related to a specific component?

Yes, the single and multi-line code snippets

What did you expect to happen? What happened instead? What would you like to see changed?

The pseudo element for the text fade effect blends with the background

What browser are you working in?

Safari

Steps to reproduce the issue

1. Step one - Using safari browser http://react.carbondesignsystem.com/?path=/story/codesnippet--multi-line

Additional information

• Screenshots or code

[jendowns]

I can help with this one 👍 Opening a PR shortly.