fix: embedded styles

[scissorsneedfoodtoo]

Checklist:

• [x] I have read freeCodeCamp's contribution guidelines.
• [x] My pull request has a descriptive title (not a vague title like Update index.md)

Related to https://github.com/freeCodeCamp/news-theme/pull/121

This PR adjusts some of the styles for the Discourse comments iframe for Chinese News.

Here's what they look like now:

And this is what they should look like after these updates:

But I wasn't able to test this locally due to CORS issues. Instead I used the dev console to play with the different styles.

[ahmaxed]

LGMT thanks for the quick fix.