sets color on divs in chapter list items with filter

[06chaynes]

Adds:

.chapter li.chapter-item div {
    color: var(--sidebar-fg);
    filter: brightness(60%);
}

to oranda-css/mdbook-theme/css/chrome.css

Fixes #654 because currently the div in the list item is inheriting from:

.chapter li {
    display: flex;
    color: var(--sidebar-non-existant);
}

Produces:

[manyinsects]

Thanks so much for all of these extremely good PRs! Is there any way we can send you some stickers or something to show some appreciation for your work?

[06chaynes]

Thanks so much for all of these extremely good PRs! Is there any way we can send you some stickers or something to show some appreciation for your work?

Thank you, means a lot! I'm more than happy to contribute to a project when and where I find I am able to do so.

Looking forward to the next release!