See attachments.
The idea is to use less contrast for the pilcrow. The whitespace.el
colors do the exact opposite: they emphasize the whitespace over the
normal text, which is great if and only if you want to just check
whitespace and then turn it off again.
Hmmm, yes, it looks good, but lightgrey is a problem with dark
background and a white foreground, as lightgrey and white have low
contrast.
Low contrast is precisely what I wanted to achieve.
The extra paragraph marks don't need to stand out. The text being
edited needs to be prominent.