As you probably know, I’m using SyntaxHighlighter Evolved to post syntax-highlighted code. Some people mailed me, that in some of my posted code the underscores are not visible (although copy&paste works). Well, the culprit is the line-height attribute of the SyntaxHighlighter Evolved cascading stylesheet: Simply increasing the line-height from the default 1.1em to 1.21em in wp-content/plugins/syntaxhighlighter/syntaxhighlighter/styles/shCore.css did the trick.