I’m surprised this fails. The book executes this code when it’s run and that regexp should be correct.
Without the %r{..}x formatting, the regular expression in the book is:
regexp = /<span[^>]*>.*1\.23.*<\/span>/
And this does match the two strings in the book:
> regexp.match?('<span style="font-family: monospace">1.23</span>')
=> true
> regexp.match?('<span class="mono">1.23</span>')
=> true
I did notice that copying and pasting from the PDF doesn’t copy the regular expression properly. Unfortunately, the tools I use to build the book result in weird uncopyable code blocks.
Can you try copying the code straight from the .zip files and see what happens?