Might be a nicer UX for the copy to clipboard buttons to only appear on sourceCode blocks and also for them to only appear on mouseover. I achieved this with simple custom CSS, but may be worth considering as default?

pre .copy button {
  visibility: hidden;
}

div.sourceCode:hover > pre .copy button {
  visibility: visible;
}

Also, would be nicer for the copy button to remain fixed when code blocks are scrolled, similar to gitbook. Haven't yet worked out the custom css to make that happen.

By filing an issue to this repo, I promise that

• I have fully read the issue guide at https://yihui.org/issue/.
• I have provided the necessary information about my issue.
  • If I'm asking a question, I have already asked it on Stack Overflow or RStudio Community, waited for at least 24 hours, and included a link to my question there.
  • If I'm filing a bug report, I have included a minimal, self-contained, and reproducible example, and have also included xfun::session_info('bookdown'). I have upgraded all my packages to their latest versions (e.g., R, RStudio, and R packages), and also tried the development version: remotes::install_github('rstudio/bookdown').
  • If I have posted the same issue elsewhere, I have also mentioned it in this issue.
• I have learned the Github Markdown syntax, and formatted my issue correctly.

I understand that my issue may be closed if I don't fulfill my promises.