There are a few things in my personal CSS file that I thought we could move to the global CSS, if that's okay with everyone:
1. Stub link coloring
#content_body a.stub { color: #D93; }
This is a default feature in most other skins, no idea why it is missing from Carbon. The software can color wikilinks differently if the target page is smaller than a certain number of bytes (1 character is usually 1 byte) set in the preferences. The threshold is a per-user setting and disabled entirely by default, so this change wouldn't affect many people.
2. Source code area background color
.css, .source-css, .javascript, .source-javascript, .lua, .source-lua { color: #000; background-color: #F9F9F9; }
We have the nice syntax highlighting extension, but the code colors are meant for white background, not black. Some text is not even readable at all on black background. This changes the background color of CSS, JavaScript and Lua code blocks to white, which admittedly doesn't look great, but makes the text readable again.
3. Diff readability improvement
ins { text-decoration: underline !important; } del { text-decoration: line-through !important; } td.diff-context { color: #777; }
This increases the contrast of diff text, and underlines/strikethroughs inserted/deleted text. Insertions and deletions are currently only highlighted by bold text and a slightly different background color, which are sometimes hard to see.
4. User name coloring by group
(see my CSS file for full code)
Changes the color of user links based on their groups, like on the forums. The user lists have to be entered manually in the CSS file, which is why I haven't added contribs yet, though it might be possible to automate this with JavaScript somehow.
Oh, and I gave bots a pink name.
None of these changes would be visible to the average reader, because most people don't look at page histories or CSS code, so I don't think we need to worry that much about what the general public would think of these, because the general public would probably not even notice.