General: Text contrast in codeblocks - HTML Cheatsheets

[cmadland]

HTML cheatsheets on https://rstudio.github.io/cheatsheets contain codeblocks highlighted in a black outline and with text that is difficult or impossible to read due to low or no contrast with page background.

Example from https://rstudio.github.io/cheatsheets/html/data-transformation.html -