Disqus embed color scheme breaks on toggle

[wjh18]

Describe the bug
Disqus auto-detects a site's color scheme and displays the embed with the appropriate contrast. When the color scheme is manually toggled via the theme's light/dark mode switcher, the Disqus embed is not toggled with it to the opposite color scheme and is difficult to read.

To Reproduce
Steps to reproduce the behavior:

1. Load a post with Disqus comments. The embed should look good.
2. Toggle the color scheme to the opposite one without reloading the page.
3. The embed should now have multiple elements with insufficient contrast.
4. Reload the page and the color scheme that was just not working should show sufficient contrast.

Expected behavior
The body of the iframe embed has a class light or dark which controls the color scheme. Target this element with JS and toggle the class when the dark/light mode switch is toggled by a user.

[wjh18]

Fixed in above merge