We don't have very many participants in the project-wide community at the English Wikibooks and very few of those have the technical knowledge or desire to worry about the site JavaScript or CSS. I recently noticed that the vertical border between tabs under the default Vector skin is missing entirely under Internet Explorer 8, but only when logged out. Strangely enough the borders appear when logged in. No problems under Firefox either way. I don't experience any problems at any other Wikimedia site. I was wondering if anyone had any insights as to what could cause this.
-- Adrignola