Illegible text for light/dark mode

Some colour choices make text very difficult / impossible to read depending on light/dark mode selection. https://www.boost.org/doc/libs/latest/tools/build/doc/html/index.html includes examples of the following cases. Code blocks in light mode have a black background, while the contained text is different shades of dark grays. Note that some inline code has a light background with black outline, so a white text would require those to be darkened. The "positive" blocks (light green) in dark mode clash with the (default?) white text that is sometimes used, e.g. in section 3.2.1.