Overlapping Columns: Paragraphs should inherit container background

[melchoyce]

Describe the bug
When you create an overlapping columns block, and add a paragraph to the column that is overlapping, it includes a background color so the text can always be read:

To Reproduce
Steps to reproduce the behavior:

1. Create a new post or page.
2. Add a cover block, and select a background color that isn't green.
3. Add a columns block inside of the cover block, and select the "overlapping" block style.
4. Add something like an image to the left column, and a paragraph to the right column.
5. See that the paragraph's background color is green, not the color you chose for your cover block.

Expected behavior
I think we should inherit that color from the container's background, instead of always using green.

Editor version (please complete the following information):

• WordPress version: 5.5.1
• Gutenberg version: 9.2.1

Desktop (please complete the following information):

• OS: macOS 10.15.6
• Browser: Chrome 86.0.4240.80 (Official Build) (x86_64)

[carolinan]

The cover block and group block does not have the same CSS classes to identify the background color, so this needs careful testing.
WordPress/gutenberg#21439

[carolinan]

Because the blocks are nested in several levels, this is only possible if the outer block has a palette color, not a custom color.
I'm not sure it is worth the extra CSS, but will do a PR.

[melchoyce]

Since this seems to be more of a hassle than it's worth, and folks can change the background color manually, I'm going to close this issue.