How can I ignore leading and trailing linebreaks within an html “code” block using css, javascript or jquery?

Question

In my HTML source code, I have a code block like the following (I use showdown and highlight.js on this page):

double myNum         


        

Answer 1

Here's another approach using Javascript that also solves the problem:

Someone else posted this, then deleted their answer, but I thought it was worth preserving.